I installed a wireless SenseStat last fall on my 39' foot diesel pusher. Works great! Easy install.
http://www.mobileawareness.com/sensestat/Backup sensors are wireless and get power from your reverse lights (so they turn on when you put it into reverse). Wireless install made it easy. It comes with little brackets to house the sensors, I was originally thinking about drilling 1" hole into the fiberglass, but instead went with the brackets, it was a lot easier, still looks good.
You can search online for folks that sell them, search for "mobile awareness sensestat" on google.
Let me know if you have more questions.