I've never really been sure if this is the proper way to handle add-ons, but I think the method you're supposed to use is to load fort joy and edit stats/models/animations from there. If there's a way to edit these things and apply them without needing to load a level,I'd much prefer to do that.

That being said, the engine crashes on loading any map. I have an old add-on I made a year or so back, and trying to load it back up to fix some things is impossible as trying to load a level crashes the editor after displaying a huge number of errors. Is there a modern, up to date guide I can follow step by step from scratch to try to design a proper add-on? The guides I have seen are horribly out of date and everyone is required to point the folders in the correct location for definitive edition, some other threads suggest other strange workarounds involving anti-virus and windows permissions. None of these guides have helped me correct this strange crash, and I was able to get things to work a year and a half ago. Any help would be much appreciated.