One local racer was essentially in the same situation you are -- he was in a wheel chair, and had very, very limited use of his arms, and essentially no use of his fingers...
He had someone rig up a ONE-Stick radio (worked exactly like a computer joystick) with a small cradle on top of the "stick", with the radio on a base to rest either on his lap or on a shelf on the arm of the wheelchair.
With that setup, he was able to race NITRO and ELECTRIC vehicles ranging from touring cars to a T-Maxx...
Get a good "pit crew" and GO FOR IT!
"If you cannot win, make the one ahead of you break the record."
Biff Racing Team #420 (Ah... The "good old days"...)
The local indoor Offroad Track: The RC Race Barn
TLR22-3.0, TLR22T-2.0, TLR22SCT-1.0