Animating customizable character (switching out parts) with Mecanim

I'm trying to create a character where the legs, arms, torso and head are all separate models.

I want to do this so that players can customize their character by swapping out parts of their character for other parts. So in the end I'll have multiple prefabs of different arms, multiple prefabs of different legs, etc... which will be instantiated based on what the player chooses.

Of course they'll all be the same size.

My question is,

1) Should each body part be skinned to its own bone?

2) How would Mecanim handle this? I can't rig an avatar if all my bones are in different models, right?

Thanks