Several months ago I installed an inexpensive VR3 rearview monitor and camera I found online. The monitor lasted for a few months and died. It was only a 2.5" monitor but did allow me to see the hitch ball as I moved under the A-frame and made hitching much easier.
Recently, I bid on a 7" monitor, that is inside a rearview mirror, on E-Bay and won the auction. I have installed the new monitor and the camera that came with it. The license plate camera that came with the old system is still working so I kept it and installed the new camera on the back of the coach just below the shore power connection. The monitor includes a remote that allows you to switch between the two cameras. Now I have the ability to see the ball while hitching and then switch to the coach camera to see what is going on behind me.
Here's a link with pictures:
http://www.geocities.com/fulltimedre.../Rear_vue.html