I have tried to get someone interested in this concept. I already do this with the WII, I put the Nunchuck on the floor and use my feet to control the motion.
Why is everyone always 100% focussed on trying to cram everything into one controller? Why not move the motion controls to the feet and have a slimmer, easer to hold controller for aiming/firing?
I am very interested in pursuing this concept and have the resources to help with some of the research costs.