Oops, I forgot that the game uses a bit of a wonky system for storing inventory. I'll make sure to include an update for this within the next few days.
And thanks for including that info on alternative installation methods. It looks like it can be used to install Feeder Expansion just fine, so I'll consider also including a patch file with the update. It's still not ideal though since it only allows a single mod to be installed with that method, though it's better than nothing I suppose. Still waiting to see if noone will change the policy for distributing modded games / swap to a setup that makes installing mods easier and with better compatibility 🙏