I tested this on my computer, and you can actually remove all the files except level.dat from inside the menu simulation save files, and they still work.
This would allow you to decrease the mod file size a bit, so why not?

I could likely do that, but it would not be much of a difference. The level.dat is always the biggest file by a massive margin, so first priority is to reduce that. But if you have more questions, rather try to find me on the Factorio Discord. I go by the same name there, and there is a very helpful channel there called mod-making too.

Yeah, I forgot about discord lol, should probably have done that from the start