This may be understood as a feature request aswell.
I think it should be possible for divers to change uniforms during a mission.

For instance, I want divers to move up to the coast in an SDV, then change to combat fatigues or something. This does not work.

Note that trying to put a fatigue in a worn wetsuit causes uniform alchemy and transforms it into another wetsuit. Can cause CTD. I reported this in another issue.