diff --git a/Cargo.lock b/Cargo.lock
index fbb68b0..01d5329 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -762,6 +762,7 @@ name = "cuprate-rpc-types"
 version = "0.0.0"
 dependencies = [
  "cuprate-epee-encoding",
+ "cuprate-fixed-bytes",
  "monero-serai",
  "paste",
  "serde",
diff --git a/net/fixed-bytes/Cargo.toml b/net/fixed-bytes/Cargo.toml
index e9985e8..4c5a1af 100644
--- a/net/fixed-bytes/Cargo.toml
+++ b/net/fixed-bytes/Cargo.toml
@@ -16,4 +16,4 @@ bytes = { workspace = true }
 serde = { workspace = true, features = ["derive"], optional = true }
 
 [dev-dependencies]
-serde_json = { workspace = true, features = ["std"] }
\ No newline at end of file
+serde_json = { workspace = true, features = ["std"] }
diff --git a/net/fixed-bytes/src/lib.rs b/net/fixed-bytes/src/lib.rs
index 370b881..2e8f1bc 100644
--- a/net/fixed-bytes/src/lib.rs
+++ b/net/fixed-bytes/src/lib.rs
@@ -12,6 +12,7 @@ use serde::{Deserialize, Deserializer, Serialize};
 
 #[cfg_attr(feature = "std", derive(thiserror::Error))]
 #[cfg_attr(feature = "serde", derive(Deserialize, Serialize))]
+#[derive(Clone, Eq, PartialEq, PartialOrd, Ord, Hash)]
 pub enum FixedByteError {
     #[cfg_attr(
         feature = "std",
@@ -48,7 +49,7 @@ impl Debug for FixedByteError {
 ///
 /// Internally this is just a wrapper around [`Bytes`], with the constructors checking that the length is equal to `N`.
 /// This implements [`Deref`] with the target being `[u8; N]`.
-#[derive(Debug, Clone, Eq, PartialEq)]
+#[derive(Debug, Default, Clone, Eq, PartialEq, PartialOrd, Ord, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize))]
 #[cfg_attr(feature = "serde", serde(transparent))]
 #[repr(transparent)]
@@ -115,7 +116,7 @@ impl<const N: usize> TryFrom<Vec<u8>> for ByteArray<N> {
     }
 }
 
-#[derive(Debug, Clone, Eq, PartialEq)]
+#[derive(Debug, Default, Clone, Eq, PartialEq, PartialOrd, Ord, Hash)]
 #[cfg_attr(feature = "serde", derive(Serialize))]
 #[cfg_attr(feature = "serde", serde(transparent))]
 #[repr(transparent)]
diff --git a/rpc/types/Cargo.toml b/rpc/types/Cargo.toml
index c088e4d..1176526 100644
--- a/rpc/types/Cargo.toml
+++ b/rpc/types/Cargo.toml
@@ -10,11 +10,12 @@ keywords    = ["cuprate", "rpc", "types", "monero"]
 
 [features]
 default = ["serde", "epee"]
-serde   = ["dep:serde"]
+serde   = ["dep:serde", "cuprate-fixed-bytes/serde"]
 epee    = ["dep:cuprate-epee-encoding"]
 
 [dependencies]
 cuprate-epee-encoding = { path = "../../net/epee-encoding", optional = true }
+cuprate-fixed-bytes   = { path = "../../net/fixed-bytes" }
 
 monero-serai = { workspace = true }
 paste        = { workspace = true }
diff --git a/rpc/types/README.md b/rpc/types/README.md
index 21905fa..eb8da01 100644
--- a/rpc/types/README.md
+++ b/rpc/types/README.md
@@ -64,6 +64,20 @@ These mixed types are:
 
 TODO: we need to figure out a type that (de)serializes correctly, `String` errors with `serde_json`
 
+# Fixed byte containers
+TODO
+
+<!--
+
+Some fields within requests/responses are containers, but fixed in size.
+
+For example, [`crate::json::GetBlockTemplateResponse::prev_hash`] is always a 32-byte hash.
+
+In these cases, stack allocated types like `cuprate_fixed_bytes::StrArray`
+will be used instead of a more typical [`String`] for optimization reasons.
+
+-->
+
 # Feature flags
 List of feature flags for `cuprate-rpc-types`.
 
diff --git a/rpc/types/src/bin.rs b/rpc/types/src/bin.rs
index 02be193..3dcfb96 100644
--- a/rpc/types/src/bin.rs
+++ b/rpc/types/src/bin.rs
@@ -3,6 +3,11 @@
 //! All types are originally defined in [`rpc/core_rpc_server_commands_defs.h`](https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server_commands_defs.h).
 
 //---------------------------------------------------------------------------------------------------- Import
+use cuprate_fixed_bytes::ByteArrayVec;
+
+#[cfg(feature = "epee")]
+use cuprate_epee_encoding::container_as_blob::ContainerAsBlob;
+
 use crate::{
     base::{AccessResponseBase, ResponseBase},
     defaults::{default_false, default_height, default_string, default_vec, default_zero},
@@ -22,16 +27,13 @@ define_request_and_response! {
     core_rpc_server_commands_defs.h => 162..=262,
     GetBlocks,
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_zero"))]
-        requested_info: u8 = default_zero(),
-        // TODO: This is a `std::list` in `monerod` because...?
-        block_ids: Vec<[u8; 32]>,
+        requested_info: u8 = default_zero(), "default_zero",
+        // FIXME: This is a `std::list` in `monerod` because...?
+        block_ids: ByteArrayVec<32>,
         start_height: u64,
         prune: bool,
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        no_miner_tx: bool = default_false(),
-        #[cfg_attr(feature = "serde", serde(default = "default_zero"))]
-        pool_info_since: u64 = default_zero(),
+        no_miner_tx: bool = default_false(), "default_false",
+        pool_info_since: u64 = default_zero(), "default_zero",
     },
     // TODO: this has custom epee (de)serialization.
     // <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server_commands_defs.h#L242-L259>
@@ -67,16 +69,17 @@ define_request_and_response! {
     core_rpc_server_commands_defs.h => 309..=338,
     GetHashes,
     Request {
-        block_ids: Vec<[u8; 32]>,
+        block_ids: ByteArrayVec<32>,
         start_height: u64,
     },
     AccessResponseBase {
-        m_blocks_ids: Vec<[u8; 32]>,
+        m_blocks_ids: ByteArrayVec<32>,
         start_height: u64,
         current_height: u64,
     }
 }
 
+#[cfg(not(feature = "epee"))]
 define_request_and_response! {
     get_o_indexesbin,
     cc73fe71162d564ffda8e549b79a350bca53c454 =>
@@ -91,6 +94,21 @@ define_request_and_response! {
     }
 }
 
+#[cfg(feature = "epee")]
+define_request_and_response! {
+    get_o_indexesbin,
+    cc73fe71162d564ffda8e549b79a350bca53c454 =>
+    core_rpc_server_commands_defs.h => 487..=510,
+    GetOutputIndexes,
+    #[derive(Copy)]
+    Request {
+        txid: [u8; 32],
+    },
+    AccessResponseBase {
+        o_indexes: Vec<u64> as ContainerAsBlob<u64>,
+    }
+}
+
 define_request_and_response! {
     get_outsbin,
     cc73fe71162d564ffda8e549b79a350bca53c454 =>
@@ -98,8 +116,7 @@ define_request_and_response! {
     GetOuts,
     Request {
         outputs: Vec<GetOutputsOut>,
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        get_txid: bool = default_false(),
+        get_txid: bool = default_false(), "default_false",
     },
     AccessResponseBase {
         outs: Vec<OutKeyBin>,
@@ -113,7 +130,7 @@ define_request_and_response! {
     GetTransactionPoolHashes,
     Request {},
     AccessResponseBase {
-        tx_hashes: Vec<[u8; 32]>,
+        tx_hashes: ByteArrayVec<32>,
     }
 }
 
diff --git a/rpc/types/src/json.rs b/rpc/types/src/json.rs
index b5b53c9..2e7aa82 100644
--- a/rpc/types/src/json.rs
+++ b/rpc/types/src/json.rs
@@ -49,8 +49,33 @@ define_request_and_response! {
         // $FIELD_NAME: $FIELD_TYPE,
         // ```
         // The struct generated and all fields are `pub`.
-        extra_nonce: String,
-        prev_block: String,
+
+        // This optional expression can be placed after
+        // a `field: field_type`. this indicates to the
+        // macro to (de)serialize this field using this
+        // default expression if it doesn't exist in epee.
+        //
+        // See `cuprate_epee_encoding::epee_object` for info.
+        //
+        // The default function must be specified twice:
+        //
+        // 1. As an expression
+        // 2. As a string literal
+        //
+        // For example: `extra_nonce: String /* = default_string(), "default_string" */,`
+        //
+        // This is a HACK since `serde`'s default attribute only takes in
+        // string literals and macros (stringify) within attributes do not work.
+        extra_nonce: String /* = default_expression, "default_literal" */,
+
+        // Another optional expression:
+        // This indicates to the macro to (de)serialize
+        // this field as another type in epee.
+        //
+        // See `cuprate_epee_encoding::epee_object` for info.
+        prev_block: String /* as Type */,
+
+        // Regular fields.
         reserve_size: u64,
         wallet_address: String,
     },
@@ -197,8 +222,7 @@ define_request_and_response! {
     GetLastBlockHeader,
     #[derive(Copy)]
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        fill_pow_hash: bool = default_false(),
+        fill_pow_hash: bool = default_false(), "default_false",
     },
     AccessResponseBase {
         block_header: BlockHeader,
@@ -213,8 +237,7 @@ define_request_and_response! {
     Request {
         hash: String,
         hashes: Vec<String>,
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        fill_pow_hash: bool = default_false(),
+        fill_pow_hash: bool = default_false(), "default_false",
     },
     AccessResponseBase {
         block_header: BlockHeader,
@@ -230,8 +253,7 @@ define_request_and_response! {
     #[derive(Copy)]
     Request {
         height: u64,
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        fill_pow_hash: bool = default_false(),
+        fill_pow_hash: bool = default_false(), "default_false",
     },
     AccessResponseBase {
         block_header: BlockHeader,
@@ -247,8 +269,7 @@ define_request_and_response! {
     Request {
         start_height: u64,
         end_height: u64,
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        fill_pow_hash: bool = default_false(),
+        fill_pow_hash: bool = default_false(), "default_false",
     },
     AccessResponseBase {
         headers: Vec<BlockHeader>,
@@ -264,12 +285,9 @@ define_request_and_response! {
         // `monerod` has both `hash` and `height` fields.
         // In the RPC handler, if `hash.is_empty()`, it will use it, else, it uses `height`.
         // <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server.cpp#L2674>
-        #[cfg_attr(feature = "serde", serde(default = "default_string"))]
-        hash: String = default_string(),
-        #[cfg_attr(feature = "serde", serde(default = "default_height"))]
-        height: u64 = default_height(),
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        fill_pow_hash: bool = default_false(),
+        hash: String = default_string(), "default_string",
+        height: u64 = default_height(), "default_height",
+        fill_pow_hash: bool = default_false(), "default_false",
     },
     AccessResponseBase {
         blob: String,
@@ -287,7 +305,7 @@ define_request_and_response! {
     GetConnections,
     Request {},
     ResponseBase {
-        // TODO: This is a `std::list` in `monerod` because...?
+        // FIXME: This is a `std::list` in `monerod` because...?
         connections: Vec<ConnectionInfo>,
     }
 }
@@ -405,8 +423,7 @@ define_request_and_response! {
     core_rpc_server_commands_defs.h => 2096..=2116,
     FlushTransactionPool,
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_vec"))]
-        txids: Vec<String> = default_vec::<String>(),
+        txids: Vec<String> = default_vec::<String>(), "default_vec",
     },
     #[derive(Copy)]
     #[cfg_attr(feature = "serde", serde(transparent))]
@@ -461,12 +478,12 @@ define_request_and_response! {
     ResponseBase {
         version: u32,
         release: bool,
-        #[serde(skip_serializing_if = "is_zero", default = "default_zero")]
-        current_height: u64 = default_zero(),
-        #[serde(skip_serializing_if = "is_zero", default = "default_zero")]
-        target_height: u64 = default_zero(),
-        #[serde(skip_serializing_if = "Vec::is_empty", default = "default_vec")]
-        hard_forks: Vec<HardforkEntry> = default_vec(),
+        #[serde(skip_serializing_if = "is_zero")]
+        current_height: u64 = default_zero(), "default_zero",
+        #[serde(skip_serializing_if = "is_zero")]
+        target_height: u64 = default_zero(), "default_zero",
+        #[serde(skip_serializing_if = "Vec::is_empty")]
+        hard_forks: Vec<HardforkEntry> = default_vec(), "default_vec",
     }
 }
 
@@ -521,9 +538,9 @@ define_request_and_response! {
         height: u64,
         next_needed_pruning_seed: u32,
         overview: String,
-        // TODO: This is a `std::list` in `monerod` because...?
+        // FIXME: This is a `std::list` in `monerod` because...?
         peers: Vec<SyncInfoPeer>,
-        // TODO: This is a `std::list` in `monerod` because...?
+        // FIXME: This is a `std::list` in `monerod` because...?
         spans: Vec<Span>,
         target_height: u64,
     }
@@ -588,8 +605,7 @@ define_request_and_response! {
     PruneBlockchain,
     #[derive(Copy)]
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        check: bool = default_false(),
+        check: bool = default_false(), "default_false",
     },
     #[derive(Copy)]
     ResponseBase {
@@ -623,10 +639,8 @@ define_request_and_response! {
     FlushCache,
     #[derive(Copy)]
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        bad_txs: bool = default_false(),
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        bad_blocks: bool = default_false(),
+        bad_txs: bool = default_false(), "default_false",
+        bad_blocks: bool = default_false(), "default_false",
     },
     ResponseBase {}
 }
diff --git a/rpc/types/src/macros.rs b/rpc/types/src/macros.rs
index 31bc6be..e130138 100644
--- a/rpc/types/src/macros.rs
+++ b/rpc/types/src/macros.rs
@@ -45,7 +45,7 @@
 /// would trigger the different branches.
 macro_rules! define_request_and_response {
     (
-        // The markdown tag for Monero RPC documentation. Not necessarily the endpoint.
+        // The markdown tag for Monero daemon RPC documentation. Not necessarily the endpoint.
         $monero_daemon_rpc_doc_link:ident,
 
         // The commit hash and  `$file.$extension` in which this type is defined in
@@ -67,8 +67,10 @@ macro_rules! define_request_and_response {
         Request {
             // And any fields.
             $(
-                $( #[$request_field_attr:meta] )*
-                $request_field:ident: $request_field_type:ty $(= $request_field_type_default:expr)?,
+                $( #[$request_field_attr:meta] )* // Field attribute.
+                $request_field:ident: $request_field_type:ty // field_name: field type
+                $(as $request_field_type_as:ty)? // (optional) alternative type (de)serialization
+                $(= $request_field_type_default:expr, $request_field_type_default_string:literal)?, // (optional) default value
             )*
         },
 
@@ -78,7 +80,9 @@ macro_rules! define_request_and_response {
             // And any fields.
             $(
                 $( #[$response_field_attr:meta] )*
-                $response_field:ident: $response_field_type:ty $(= $response_field_type_default:expr)?,
+                $response_field:ident: $response_field_type:ty
+                $(as $response_field_type_as:ty)?
+                $(= $response_field_type_default:expr, $response_field_type_default_string:literal)?,
             )*
         }
     ) => { paste::paste! {
@@ -99,7 +103,9 @@ macro_rules! define_request_and_response {
             [<$type_name Request>] {
                 $(
                     $( #[$request_field_attr] )*
-                    $request_field: $request_field_type $(= $request_field_type_default)?,
+                    $request_field: $request_field_type
+                    $(as $request_field_type_as)?
+                    $(= $request_field_type_default, $request_field_type_default_string)?,
                 )*
             }
         }
@@ -125,7 +131,9 @@ macro_rules! define_request_and_response {
             $response_base_type => [<$type_name Response>] {
                 $(
                     $( #[$response_field_attr] )*
-                    $response_field: $response_field_type $(= $response_field_type_default)?,
+                    $response_field: $response_field_type
+                    $(as $response_field_type_as)?
+                    $(= $response_field_type_default, $response_field_type_default_string)?,
                 )*
             }
         }
@@ -166,7 +174,9 @@ macro_rules! __define_request {
             $(
                 $( #[$field_attr:meta] )* // field attributes
                 // field_name: FieldType
-                $field:ident: $field_type:ty $(= $field_default:expr)?,
+                $field:ident: $field_type:ty
+                $(as $field_as:ty)?
+                $(= $field_default:expr, $field_default_string:literal)?,
                 // The $field_default is an optional extra token that represents
                 // a default value to pass to [`cuprate_epee_encoding::epee_object`],
                 // see it for usage.
@@ -180,6 +190,7 @@ macro_rules! __define_request {
         pub struct $t {
             $(
                 $( #[$field_attr] )*
+                $(#[cfg_attr(feature = "serde", serde(default = $field_default_string))])?
                 pub $field: $field_type,
             )*
         }
@@ -188,7 +199,9 @@ macro_rules! __define_request {
         ::cuprate_epee_encoding::epee_object! {
             $t,
             $(
-                $field: $field_type $(= $field_default)?,
+                $field: $field_type
+                $(as $field_as)?
+                $(= $field_default)?,
             )*
         }
     };
@@ -218,7 +231,9 @@ macro_rules! __define_response {
             // See [`__define_request`] for docs, this does the same thing.
             $(
                 $( #[$field_attr:meta] )*
-                $field:ident: $field_type:ty $(= $field_default:expr)?,
+                $field:ident: $field_type:ty
+                $(as $field_as:ty)?
+                $(= $field_default:expr, $field_default_string:literal)?,
             )*
         }
     ) => {
@@ -226,6 +241,7 @@ macro_rules! __define_response {
         pub struct $t {
             $(
                 $( #[$field_attr] )*
+                $(#[cfg_attr(feature = "serde", serde(default = $field_default_string))])?
                 pub $field: $field_type,
             )*
         }
@@ -234,7 +250,9 @@ macro_rules! __define_response {
         ::cuprate_epee_encoding::epee_object! {
             $t,
             $(
-                $field: $field_type $($field_default)?,
+                $field: $field_type
+                $(as $field_as)?
+                $(= $field_default)?,
             )*
         }
     };
@@ -250,7 +268,9 @@ macro_rules! __define_response {
             // See [`__define_request`] for docs, this does the same thing.
             $(
                 $( #[$field_attr:meta] )*
-                $field:ident: $field_type:ty $(= $field_default:expr)?,
+                $field:ident: $field_type:ty
+                $(as $field_as:ty)?
+                $(= $field_default:expr, $field_default_string:literal)?,
             )*
         }
     ) => {
@@ -261,6 +281,7 @@ macro_rules! __define_response {
 
             $(
                 $( #[$field_attr] )*
+                $(#[cfg_attr(feature = "serde", serde(default = $field_default_string))])?
                 pub $field: $field_type,
             )*
         }
@@ -269,7 +290,9 @@ macro_rules! __define_response {
         ::cuprate_epee_encoding::epee_object! {
             $t,
             $(
-                $field: $field_type $(= $field_default)?,
+                $field: $field_type
+                $(as $field_as)?
+                $(= $field_default)?,
             )*
             !flatten: base: $base,
         }
diff --git a/rpc/types/src/other.rs b/rpc/types/src/other.rs
index 03cb05d..5ad2caa 100644
--- a/rpc/types/src/other.rs
+++ b/rpc/types/src/other.rs
@@ -36,12 +36,9 @@ define_request_and_response! {
         // FIXME: this is documented as optional but it isn't serialized as an optional
         // but it is set _somewhere_ to false in `monerod`
         // <https://github.com/monero-project/monero/blob/cc73fe71162d564ffda8e549b79a350bca53c454/src/rpc/core_rpc_server_commands_defs.h#L382>
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        decode_as_json: bool = default_false(),
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        prune: bool = default_false(),
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        split: bool = default_false(),
+        decode_as_json: bool = default_false(), "default_false",
+        prune: bool = default_false(), "default_false",
+        split: bool = default_false(), "default_false",
     },
     AccessResponseBase {
         txs_as_hex: Vec<String>,
@@ -82,10 +79,8 @@ define_request_and_response! {
     SendRawTransaction,
     Request {
         tx_as_hex: String,
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        do_not_relay: bool = default_false(),
-        #[cfg_attr(feature = "serde", serde(default = "default_true"))]
-        do_sanity_checks: bool = default_true(),
+        do_not_relay: bool = default_false(), "default_false",
+        do_sanity_checks: bool = default_true(), "default_true",
     },
     AccessResponseBase {
         double_spend: bool,
@@ -167,10 +162,8 @@ define_request_and_response! {
     core_rpc_server_commands_defs.h => 1369..=1417,
     GetPeerList,
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_true"))]
-        public_only: bool = default_true(),
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        include_blocked: bool = default_false(),
+        public_only: bool = default_true(), "default_true",
+        include_blocked: bool = default_false(), "default_false",
     },
     ResponseBase {
         white_list: Vec<Peer>,
@@ -208,8 +201,7 @@ define_request_and_response! {
     core_rpc_server_commands_defs.h => 1494..=1517,
     SetLogCategories,
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_string"))]
-        categories: String = default_string(),
+        categories: String = default_string(), "default_string",
     },
     ResponseBase {
         categories: String,
@@ -300,8 +292,7 @@ define_request_and_response! {
     core_rpc_server_commands_defs.h => 1876..=1903,
     OutPeers,
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_true"))]
-        set: bool = default_true(),
+        set: bool = default_true(), "default_true",
         out_peers: u32,
     },
     ResponseBase {
@@ -345,8 +336,7 @@ define_request_and_response! {
     Update,
     Request {
         command: String,
-        #[cfg_attr(feature = "serde", serde(default = "default_string"))]
-        path: String = default_string(),
+        path: String = default_string(), "default_string",
     },
     ResponseBase {
         auto_uri: String,
@@ -402,12 +392,9 @@ define_request_and_response! {
     core_rpc_server_commands_defs.h => 1419..=1448,
     GetPublicNodes,
     Request {
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        gray: bool = default_false(),
-        #[cfg_attr(feature = "serde", serde(default = "default_true"))]
-        white: bool = default_true(),
-        #[cfg_attr(feature = "serde", serde(default = "default_false"))]
-        include_blocked: bool = default_false(),
+        gray: bool = default_false(), "default_false",
+        white: bool = default_true(), "default_true",
+        include_blocked: bool = default_false(), "default_false",
     },
     ResponseBase {
         gray: Vec<PublicNode>,