Object with armature clipping through the ground plane

If I have a simple mesh, I can constrain it to stay at or above a ground plane with a few lines of python. However, when I add an armature to the mesh to allow it to deform correctly the mesh will happily clip through the ground plane. Is there a way to get a single bone in python? I looked through the API but couldn’t find anything. Is there another way that anyone can think of to keep the armature’d object from clipping through the floor?