Older post, but I'll add anyway. Sometimes the wall plate can be a pain to remove, as the hole usually isn't quite big enough to pull straight out. Try removing the bottom first then the top. On mine the 3 coax cables plug in vertically from the top. Should be enough slack as it had to be out to connect it at the factory.
Adding a sat plug to the outside of the RV is a good way of doing it, especially if the tv is fairly close to an outside wall. With a little patience a professional looking job isn't hard to do.
What I did with mine (I use a Answer sat dish) was to remove the antenna/sat connection from the wall, locate the cable that comes from the outside cable connection. Drilled a small hole next to it and stuck this cable thru the whole labeling it "outside plug". Took a short piece of coax (12" in my case) connected it where the outside cable was hooked and stuck the other end thru the hole, labeled it "cable". Now I just hook the outside cable to my sat box and plug my portable antenna into the cable connection on the outside of the trailer. With a small male to male coax connector I can then connect these to cables back together when I'm at a park that has available cable tv. No holes in the outside walls, no cable on the floor. So far works pretty well.
2011 Coachmen North Ridge 290RKD 5'er
2005 Dodge quad cab dually diesel 6'spd manual
1 weird cat with an occasional attitude problem.