I got one! :)
I chose this and it works great
https://hopkinstowingsolutions.com/products/towing-cameras/50050.htmlThey have a good video there so you can see how it works.
It has a short wire from the camera that takes 12v. They suggest attaching to an upper back clearance light for the view and also perhaps to make it really hard to steal.
I wanted to just keep it inside looking out the back window and get 12v to it another way. Done. So it is portable to use in whichever RV we are using. It sees out the window just fine. Need to make a stand for it that stays in place.
One thing is the window reflects the camera lights which you have to ignore. Water drops on window, ignore. The MH has those dark windows, so the picture there is sort of gloomy, but it is clearer with the TC.
Display is to your "device" you must use somehow while driving. I have an older small iPad that I attach to the rear view mirror with elastic bands. Portable to the truck or the MH. Plugs in to the dash cig lighter socket for keeping it charged.
You get the free app on your device (needs IOS 8 or Android 6 or newer), and select the Hopkins wifi--they give you a password in the instruction manual that comes with the camera.
Ta da! What a neat gizmo! :) Note a reviewer said there is a distance limit of about 40 ft for the wifi so he had trouble with his 35 ft 5er and the truck length, but no problem with our set-ups.