Better late than never...
You probably already got this figured out since this has been posted a while, but just in case you didn't here's another possibility (I just spent 3 hours tonight getting this figured out).
If Forest River uses a consistent set up, next to your DVD player will be two outlet jacks: one plate with 2 coaxial cable jacks (TV and Aux/Satellite) and another plate with a standard RCA jack setup with one red, one white and one yellow RCA jack.
The RCA jacks are old-school, and most new hi-def TV's don't use them anymore (the new one I just bought didn't). Most TV's now have a coaxial input, an HDMI input, and a ColorStream composite input (red, blue, green jacks). In order to work around this, plug a single RCA cable into the YELLOW jack on the wall plate next to the DVD. Then plug that cable into the GREEN jack on your TV. Then set your TV source to Video or Composite, or whatever lines up with the ColorStream input (may have to check your TV manual, or just cycle through sources on your TV while you are playing a DVD).
That should get you a video signal on your TV, while the sound plays through the camper speakers. It won't be high def, but that's because the factory DVD player is old-school.
Hope that helps, assuming you haven't already figured it out.