My backup camera stopped working so I purchased a wireless system with three cameras: right, left, and rear. I am not sure I would go the same route if to do it again, unless the receiver had video outs. I am stuck with the additional 7-inch screen for the wireless unit and would rather integrate the camera feeds into my stereo head unit or the Silverleaf VM350 I recently installed.
Perhaps try searching for a hard wired wide-angle camera that can replace your existing one