Some mods target the Mono version of the game, which is available by opting into the Steam beta branch "alternate"

OG Backpack
It's back, now with proper multiplayer support! The backpack, originally created by Tugakit and later re-uploaded by Ryebread, now features the saving of its contents for all players, not just the host.
CHANGELOG
#1.8.1
- Updated for 0.3.6 version of the game.
1.8.0
- Added synchronisation of the config from the host to the clients.
- Fixed the backpack UI scaling incorrectly.
- Fixed the cart incorrectly warning of items being placed on the pallet.
1.7.0
- Added support for up to 128 storage slots in the backpack.
- Added overflow support when buying items to use the backpack if the inventory cannot fit everything.
- Added configurable backpack search to police behaviour.
1.6.0
- Added support for configurable values.
- Made the total slot count in the backpack configurable.
- Made the keybinding for the backpack configurable.
- Added a configurable unlock requirement based on your rank.
- Moved all logging to a separate class for easier transition between Melon and BepInEx.
1.5.0
- Broke off from original repo
- Changed backpack storage component to support network syncing
- Moved patches to a separate directory