The APC can float and drive on water. It would be nice if every vehicle could.
If it turns out to be easier said than done, then how about a mod that adds like an invisible aircraft engine to every ground vehicle? The point is that all JC3 vehicles actually are amphibious, but only as long as they’re moving fast enough. Once the speed drops, they sink. So if you can’t make vehicles float like the APC, then add a way for them to have thrust.