Well, you can't say I didn't try. I was able to change the model using the same method as my viewmodels, and tested it offline with success:
However, even with preloading it didn't work in casual servers, while my viewmodels still worked there. I tried a bunch of different methods, including empty model swaps, texture edits, material edits, and finally just a straight up model edit to move the idle animation below the ground, which is what you see above.
I can give you this VPK (after putting it further in the ground) but I don't know how much good it will do. Maybe it could be preloaded into ultiduo servers or competitive ones, but Valve MM doesn't allow it.