Er, what Rave said.
Taking it a little bit further, Raven are using the Ghoul 2 tech., which actually allows you to attach separate items such as sunglasses, hats, backpacks etc. to characters, which can be shot off by the player. So the scope for attaching a variety of separate models is definitely there.
I am assuming this feature of Ghoul 2 will be implemented in JK2 - because it has been confirmed that Ghoul 2 is being used for the game's development in a preview I read somewhere.