A few questions about your Stone Rhino model:
1. does it have a mount point that would allow for torso twist?
2. has articulation of the legs been taken into account with respect to clipping with the upper hull?
3. more of a technical question, are you able to port your model into 3DSMax 2008? The workflow for import path from Maya for CryEngine2 is a rough road.
1. I could very quickly/easily modify it's base to allow for torso twisting.
2. It's modeled with animation in mind, so clipping isn't an issue.
3. That's a tough one, I could get 3DSMax 2008 and mess around with it. I know it's possible through a more universal file format like obj, bdf, or fbx. I'll see what I can come up with.