The game already stores personal equipment, but it could be improved.
Firstly, an aquanaut should take his personal equipment directly from the stores, and what you put on the sub equipment list, is just extra, that's what's on the floor on tile 1.
This way you can switch crew without updating equipment list. (so you don't take too much extra either. In 2 part missions it can blow up. I think you should be able to leave some of the surface loot in the sub)
Of course it would be convenient to have 4 profiles, as you have 4 alien types, and clicking a profile gives all aqs the right weapons.
Under the button Aquanauts should be an equip button, if you use this it is auto saved. Changes made prebattle are no longer auto saved. There should be a button however to force it.
If there is a weapon shortage, then no changes should save to your personal equipment. A permanent warning marker should be somewhere, also one in the intercept window.
If you transfer the aquanaut, his PE should follow him.
