Damian, the guys that have moved there rear brakes to the handle bar are running Rekluse or auto clutches, so moving your rear brake to the handle bar may be a challenge without one, but not imposable.
I know a guy who has only one arm and still rides and races his dirt bike. Since he has no left arm, he has moved his clutch to the right side of the bar and has staggered the front brake and clutch levers a bit, it works for him quite well, and yes he has a lot going with that one hand, and he can ride as good as too be expected. Oh and a word of advice, don't arm wrestle this guy! His right arm is a rock!
I know a guy who has only one arm and still rides and races his dirt bike. Since he has no left arm, he has moved his clutch to the right side of the bar and has staggered the front brake and clutch levers a bit, it works for him quite well, and yes he has a lot going with that one hand, and he can ride as good as too be expected. Oh and a word of advice, don't arm wrestle this guy! His right arm is a rock!