Unturned II and Unturned 3.0 are separate titles with different mechanics.
Meaning, most of your suggestions for II are going to be possibly nullified due to them being for a completely different game!
The game’s first beta isn’t even out yet, so how about giving it some time to release to see what the basic mechanics are first?
I’ve seen time and time again, suggestions that are just expansions of what 3.0 already has trying to weasel themselves into 4.0 with more specific mechanics just to seem new.
If you desperately want to suggest something, just stick to something broad and original. No need to go about suggesting realistic ideas like disease, that’s a bad idea.
TL;DR: Stop suggesting things from 3.0 with more specific mechanics when you don’t even know what the mechanics for II are going to be.