My post above was before our last trip with the camper. I did not realize how much I have come to rely on it for lane changes. The cutting out was really annoying while on a busy highway, we were in A LOT of memorial day traffic so I resolved to find something better.
After that trip I researched and I purchased this system from Amazon. The screen is larger than what I have been using but the trade off is it never cut out once on a 45 minute drive while pulling the camper AND it records if you put an SD card in it. The thing there being that while parked at a place on the drive out getting gas or food etc... if the head unit and camera have power it will record if someone hits your camper while your away..... The picture was clear, I am impressed. As with any camera the night vision distance is not at all as good as during the day but you can definitely see approaching vehicles and any traffic close to you.
All in all I am MUCH happier with this purchase though it cost a fair bit more than my $50 one:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I did not drill any holes in the camper for it either. I used 3 rows of this auto grade adhesive on the mount and put it near the top of the roof looking at a downward angle. I also put a bead of RV adhesive across the top and sides as well as the cut outs on the mount itself to keep water out:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
It has a barrel style plug so when the roof lifts if I have forgotten to unplug it no harm, it just unplugs itself.
That is exactly how I mounted my last one and it was going strong for two years.
For 12V power at the trailer I tied in to the refrigerator area as its on with the galley up or down but I added a 2amp inline fuse so it couldn't damage anything.
Routing was simple, I pushed the wire out the floor through the gas line opening. I used this stuff to protect it under the camper and brought it up the rear behind the spare tire hanger:
https://www.amazon.com/Alex-Tech-25f...10&sr=8-4&th=1