I installed a wired camera system from Rear View Safety on my TT but ran the wire from the camera across the top edge of camper, down the side and along the underbelly to the front of the camper. To secure the wire which is about as thick as Coaxial cable, I used plastic Coaxial cable ties and screwed them in to the edge molding and then used Geocel caulk to match the molding. In my Tow vehicle, I ran the wiring under the dash, then under the molding on the floor at the door, and out through a hole that pre-existed to get outside. Then under the truck to the rear bumper where I mounted the plug to attach the camera wire. To secure the wiring under the truck, I used long Zip ties that went around the frame.
Everything worked fine but a year later when I bought a new truck, I opted not to use the rear camera and took everything off the camper, replaced the edge molding and covered the hole in the aluminum siding where the camera had been mounted with a reflector. To be honest, It didn't offer me much help and I sold the camera system. Vehicles that are directly behind me I can still see with my extended side view mirrors provided they aren't tailgating. What's important to see is who is along side of you if you want/need to switch lanes.
Rear view cameras are nice in theory but how many tractor trailers do you see with a rear camera? I don't think I've ever seen one.
Also, if you're thinking about installing a camera to help back up into campsites, just practice more and take your time. If you get nervous or worried you're going to hit something, don't be afraid to stop and get out and walk back to take a look and then adjust accordingly. I have rarely seen any camper whether a newbie or a seasoned camper back in and not have to make some adjustment.