If you go up on the roof near the antenna, you should find the other end. It was pre-installed for a satellite dish/ receiver configuration. I have the Trekker cap and coax port is located inside the cabinet behind my TV
If you also have the King Jack TV antenna, you should find a power switch for the antenna somewhere. with the power on, your tv's get a signal from the antenna. with the power off, the signal comes from the cable tv jack outside. In the Sunseekers case the connection is next to the cabin door.