Guess it depends on how your RV is wired. I use Dish and the Tailgater. The Dish guys set mine up with a diplexer and a couple of short coaxes. They put one coax on the "Main", another on the Sat 1, and yet another on Sat 3 (I think). That way I can see the same channel on all three TV's, with just one connection to the Tailgater. They also needed to disconnect the short jumper at the Over Air antenna. I really cannot remember exactly why they did that. But I seem to remember they used the term "Backfeed" quite a bit.
They had a gizmo that they could use to identify which connection went where. I think they called it a "TONE tester".
Like this one. They would put a terminal end at the end of each connection that would transmit a different color. Then the meter gizmo on the input end, would identify the color that came thru that connection.
I think that would be a handy item to have.