Actually it uses its own supermodel, but I did successfully swap it out with the female one as it better suits my purposes. I also realized what was causing my other problem before: the water suit MDL (sans MDX) somehow slipped into Override. I probably dragged it in by accident, and because the space suit uses that as its supermodel, it was confusing the game.
It's always the most idiotic things that mess you up.
Check it out!
Er... don't mind the background, that was just the location of my last save.