Unless the Pro is wildly different than my Pro S, the only real problem is the inconspicuous area around the lens mount--the other panels on the sides don't surround the focus knob or the cocking lever. Same goes for the back and WLF.
I've not seen anything for the Mamiya RB series from CameraLeather. Why they support something like the Minolta Autocord but not the RB cameras is baffling. Good luck. Me? I'd go for Mack Daddy fake fur<<George Clinton and Parliament "Give Up the Funk" heard in the background>>