Make your life easier and use a wireless unit. Many options available as that is the only real option for those of us with towables. As long as there is 12v where you want to mount the camera (many just replace one of the upper running lights) you are good to go. No fuss, no holes, no crawling around underneath the unit.
2011 Jayco X19H (purchased 2015)
2008 Jayco 1007 PUP (purchased new, traded for the X19)
2012 Chev Traverse LT with TP