I just installed a backup camera on my pickup and travel trailer. Men or Women, if you are tired of your spouse "assisting," you in backing up your trailer this is the hot ticket! I read on the forum about people trying wireless camera's on trailers but due to trailer length and interference in signal they often times do not work.
I found a hard wired system on Rear View Safety.com Rear View Safety | Product | Backup Camera System | RVS-770613
I purchased the two camera system. It was very easy to install. I now have no problem hooking the trailer to the truck, and no problem backing into camp spots. I also like the fact that I don't have to judge distance between myself and the car I just past. I know when it is safe to slide back into the right hand lane, and don't need truckers to flash their lights to let me know it is safe!