My 2008 3500 DRW LTZ came with Navigation and DVD, but know back up cam. I'm able to watch movies on my head unit only in park and full time in the rear. Is there somewhere to add a back up cam feed to the factor head unit? I see there is a input for the rear seat monitor but the screen doesn't spin around and it would be a pain to try and look at it. It's only to help me hook up a trailer so once in awhile it wouldn't be a big deal. Just was curious if someone has hooked one up to factory deck.