You can just bring a satellite receiver into the RV and connect it up. It will only put out the DirecTV logo or you can click on the Menu button so you have "something" displayed on the screen. Follow the other instructions and you will have a picture on all TV's. Work on the wiring until you have a clear picture on all TV's.
If you post your coach information or post to a forum specific to your coach you may get some help on where splitters are located if the signal is handled by splitters and not some from of a video control center.