We purchased our Nomad 21' TT in March. It has a wall jack set up with 2 coaxil cable ports. The top one has a button beside it to turn on the digital antenna. The other one goes...no where! I called ...
The easy way out would be a flat video cable out a door, window, hatch, etc etc.
If you want something permanent, then that will require drilling a hole for the connection. Make sure you use butyl tape putty behind the fixture, and then seal all around with proflex rv sealant.