Does the camera need to be so high? Shortening the vertical arm will make the unit more compact and lighter. With a hand held Nadir patch shot or a Nadir adapter shot, having the camera closer to the rotator should not present an issue. You could even make the clamp and rotator scale all one piece instead of two. Smaller and lighter still.
Well, I don't want to make too many new parts. The rig is suitable for most cameras with lens ring clamp.