I recently installed the camera Baja Man linked above. I installed it in place of the center rear running light, because I wanted to limit the holes in my fiberglass body. My rv is 27.5' and reception is excellent. a very expensive camera, but I like the audio option and the cig lighter plug. It is also heavy at 1lb of bouncing mass 3" away from the rv body, which led me to worry about mounting solidly without risking cracking my fiberglass.
I used 1x4 pvc board to mount the camera to, then secured it to the rv. On the inside of the rv shell I have another piece of 1x4 pvcp. So it's a sandwich of pvc board either side of the fiberglass. I used bolts(4) and jb weld to secure camera to pvc. And then longer bolts(2 more) to hold it altogether with proflex also securing it on the outside.
3rd edit. Sorry Baja Man I didn't absorb your post very well. If you are considering that camera, I would highly recommend it. Clarity in video and audio is very good. I haven't used it at night yet, so I can't comment on that. I stick it my to the windshield when traveling and stash it behind the drivers seat when not. I thought they sent me a wrong antenna and contacted them, they responded twice (2 different people) with in a day on the weekend. But I finished unpacking and found that they give you 3 antenna, 2 hard plastic with the elbow and one metal one on a 6' wire. I use the 2 hard plastic ones and from the moment I hooked it up it has been excellent. as I said above I think it is pricey, but you get what you pay for in this instance.