I have a small door as shown on the rear photo for getting to water pump and seeing the fresh water tank. I fished the bottom camera wiring from the camera to that door area using a fish tape and it had some styrophome that I had to push through to get to it, but it worked. From that door area, I ran it down to underneath the Motorhome.
For the top camera, I have cabinets in the back wall on the inside, so I drilled through to inside the cabinets which was also in an area that had a molding to hide the wires inside the cabinet which I ran from top middle on the inside to more cabinets that go from the drivers side of the back to the floor area which I ran the wiring through to get to undernieth the Motorhome. Cannot see any wires just using what was available. Trying to run through the shell wall would have been difficult since that window was there in the back making it harder or would have just pushed straight downwards. Wasn't difficult, just took some looking around for best options of what is available to use. Coudn't tell where the house top outside red clearance lights wiring was wired from looking on the inside, so didn't know how to run with them, but figured they may go through studs or something and would never be able to duplicate that as they were wired during contruction. Would be nice having post wiring conduit in the walls for items as this, but probably not practical for cost and convenience. Even for the top camera, I likely had a good 10 foot of wire left to coil up and hide.
I trusted hard wire more than wireless due to distance but wireless may have worked fine but wanted to be sure it would work, so decided on wired system. Glad I chose this and the system really works well. I can see my back end from reciever hitch to a good 12 foot or more out using backup camera and much further using top camera. Will maybe get a front mount camera in future for parking aid in front, but will wait and see on that one. System will hold another camera with switch box that was included. Maybe mount somewhere else such as top also to see the top of mororhome? Who knows?