I'm not sure what's a bigger burden: knowing things, or the difficulty conveying this knowledge to people like you.
Your brilliant plan wouldn't work. Besides the fact that which mesh used for a creature is not saved in the game save but is instead read from the binaries (requires modding), let's just pretend that it wasn't an obstacle. Unless you mean swapping the ID numbers in the actual graphics.big archive, which is also impossible to do with a save hack, and constitutes modding, it's also extremely bad form.
Regardless, you would end up with
this. That's an animation problem.
I don't want to be that one prick who keeps going around saying "toldya so" or "I'm smarter than you" because that's not my style. It really would make my day if people would just say "oh, okay" instead of trying to be all clever.