My trailer has a outside CABLE HOOKUP point. I plug MY TV into the Antenna Panel on the inside usually right next to where your TV sits. The Antenna Wall Plate has a push button on it. If the small LED light is 'ON' push the button to turn it 'OFF' so you can see what is coming in from the CABLE outside protection. When the small light in 'ON' you can raise your roof BATWING antenna and scan for local BROADCAST TV signals from the local towns Over the Air...
The bedroom TV connection will be slaved off the Antenna Wall Panel as well... Same deal LED 'OFF' to watch CABLE TV or 'ON' to watch roof mounted BATWING antenna TV signals. You have to go to the digital TV menu and select either CABLE or ANTENNA and scan for channels just like you do from home everytime you setup for camping...
This is what the Antenna Panel looks like from google image search...

Of course trailers are all different but this is pretty much the basic method...
Roy Ken