I use a pair of wired backup cameras (both license plate frame cameras) feeding a Kenwood DDX393 double DIN DVD receiver in my Tahoe dash. One camera is mounted to the back of the Tahoe facing the hitch area, and one is mounted to the back of the trailer at about typical rearview mirror height. The wiring is simply zip tied to the trailer frame and I have a set of RCA connectors I mounted behind the bumper so I can disconnect the trailer. The camera has no problem transmitting over 40 feet of cable back to the dashboard, and the image quality is very good.
Here's the camera I use:
https://www.amazon.com/gp/product/B00GMC8QXI/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
It's a bit of a wide angle compared to your eye so you have to get used to the depth perception, but it also has servicable night vision so I don't need backup lights to get into my driveway or a spot, and I can easily hitch up without having to check where the hitch is going to stop. It is also really, really nice to have a trailer rearview camera while driving in heavy traffic... last time I drove through Seattle on I5 it was a breeze. I don't really need my extended towing mirrors any more, I don't have a blind spot to the back.