I also have the Rear View Safety system, but the hard wired version. I installed the camera it comes with under the rear center brake light using expanding rubber nuts in holes drilled into fiberglass (carefully). The display is mounted by screwing to the steel roof just above the windshield (must drop headliner just a little to access). This puts the display up where the rear view mirror would be, and it works great always running. The multiplex box that connects the camera(s) to the display is mounted inside the cub holder at the console (there is room inside). I had to order a longer cable from Rear View Safety to connect the display to the multiplex switch.
This system allows 3 cameras. Over time, I added a second cheap camera inside the rear bumper for hitch aligning and close bumper backups. I also added another wire run with a connector that is used when attaching the trailer. The trailer has another camera. So I can view the traffic, the hitch, and the trailer depending on which view I select.
I wired the first camera through the interior. In hindsight, I would have wired it underneath the Westy. The Rear View Safety cables are durable and hold up outside.