I installed a Furrion FOS48TAPK-BL that I bought on amazon.  I wired the camera in to the middle running light at the top (camera comes on when headlights are on).  The screen mounts to the windshield via suction cup.  I use it for both backing up in to the campsite and often when driving since it gives you a much better sense of what traffic is doing behind you.

Its a few $$ but I'm very happy with the quality and glad I did it.

This method does test whether or not the tail lights on the camper are functioning (and for me, this is enough of a test mid-trip when I know all lights were working the day before).  It does NOT test whether or not the brake circuit is sending and receiving the appropriate brake signal.

As mentioned earlier,I would talk to the folks at etrailer.com.  They have a lot of choices to meet your needs.

If that's all you need, then you shouldn't need to get too elaborate or pricey. Good luck with the search - hopefully installation won't be too tricky! When I installed ours in my wife's Ridgeline the receiver/screen just plugs into the cigarette lighter 12v but I had to hardwire the camera (wann't too bad, ran a line from the taillight compartment).

Go for it!

Mine's too old to use as a reference point, so am reluctant to recommend it - I would suggest spending some time on eTrailer and Amazon, and see what the current stuff is like. Lots of things to consider - where/how you'll mount the screen, removable vs fixed, size, one camera or two (some folks like to have one on the back of the trailer also, to see where you are backing once hitched up vs just using it to hook up).

I feel they're essential for solo travel, saves so much trial and error. That, with a stick marked to avoid a false hitch, and the same stick wedged  in your car brake pedal to test the brake lights, while also you are testing the turn signals, and you are all set to go.