cinbri!!!

That would take a lot of work, and I'm not sure what all files would have to be changed (Many though, I'm sure). Plus it would make it incompatible with a lot of mods because of what all had to be altered.

I don't think just a skin would cut it. The Cinbri side jaws are too much to give up.

A new playable based on the Cinbri model(s) would be a huge effort, even if you could agree on which configuration is the basic one. A playable character that has a unique model needs a large number of helmet meshes, boot meshes, body armor meshes, as well as animations for all the other weapon types they didn't already use. There are compromises whereby you restrict the things they can equip that would reduce the effort, but it's still going to be something most modders can't attempt.

Plus it would definitely not fit the story on the regular maps, so you'd probably only do this in the context of a whole new map from the Cinbri point of view. Now there's an idea for a team to take on!