Standalone Build - Do not bundle resources (just create a folder)

Does anyone know of a way to have a standalone build read Resource assets from a folder, rather than having Unity bundle them into the resources.asset file?

One use case for this is if I'd like the PC version of my game to be modable, with players able to replace assets and restart the game to see the effects.

My actual use case is a bit more complex. I've got a level editor, which allows someone to edit the custom level .json files for my game. I'd like to distribute this editor without forcing users to install Unity. It would be great if I could just distribute the .exe for the game and editor, with a resources folder, containing the art and level files, and allow the editor to modify those without recompiling the binary.

Any ideas?