I haven't done it, but can tell you how to do it. (only works with coax attached TV's)
If your camper has the following box:
Remove the jumper from the B port. Hook up your DVD / Satellite / source into the B jack and insure your power antenna is OFF (indicator light extinguished) and ALL TV's connected via coaxial cable will receive the exact same signal. Of course you'll need to tune to which ever channel the device transmits on.
If you don't have that connector plate OR can't / don't want to use the coax, then you'll need to come up with other solutions which may include splitters, running cables, or expensive wireless components.