Jim44646 is correct. The rcvr must push an 18V signal to the LNB in the dish (tailgater). This seems to be a common problems in campers not wired for SAT; this 18V gets blocked at the antenna booster. You can use any variation of splitters and jumpers to bypass the booster or run a dedicated cable.
In my old TT, I installed a SAT-rated splitter behind the booster plate on the incoming coax. Then I used two short lengths of cable: one from the splitter to the original incoming connection on the back of the booster plate, and the other from the splitter to a new wall plate that I installed next to the booster plate. The new wall plate is where the SAT rcvr gets plugged in because it bypasses the booster and the dish can now be plugged into the outside park connection.
For the connections to the TV, you can use coax from the booster wall plate and use a different type of connection from the rcvr (RCA, HDMI...). Then you just select the right input source when you turn the TV on. If your TV does not have multiple inputs available, you can run coax from both wall plates into a SAT-rated AB switch and run a single coax from that switch to your TV. Then you manually select your source at the switch.
Now open a beer, kick your feet up, and commence to do what we thought we'd be doing when we bought our rigs!