I've read lots of posts about people installing backup cameras on the back of trailers and they seem like a good idea especially since they've become so inexpensive. I've also read lots of posts where the wireless setups either weren't powerful enough to provide a consistantly good image or were affected by external interference. So I decided to go with a hard wired system. I've run lots of wires so it didn't seem like a big deal to run another couple of wires for the cameras.
I found a 7", dual input, monitor on ebay, $52 with one camera and bought a second one for $15.
I was wondering where I might mount it as I didn't want it on top of the dash but since it is about the size of my radio I decided to mount it in front on a bottom hinged bracket. Instead of hooking it to the backup lights
to "turn it on" I wired in a small switch so that I can turn the whole system on while underway to monitor out of sight traffic behind the trailer.
I havn't had a chance to use it on the trailer while underway but early indications are that it'll meet my needs. A "V1/V2" button on the monitor allows for selecting either the hitch or the rear of the trailer. 67 bucks, what a deal