Can a quadriplegic driver handle braking-Class A gas/Class C

Totally impossible to tell. In most cases a motorhome has no greater physical requirement than any other vehicle. The steering is as light, the brakes are similar as well. What I think is different is the need to move the head quite a lot to gain the required view out of the windows, the mirrors, and so on, to tell what is going on around the vehicle. You can't "add" air brakes, the vehicle either has them or doesn't. But they don't require a significantly different effort than any other brakes.

Brian