Spinningbull: I recently ran a coax from one end of our trailer to the opposite side and forward about 12' or so. I ran the cable through a storage compartment into the fridge cavity (after pulling it out) and then up into the ceiling. Getting through the ceiling was the trickiest part. It's hard to tell where they installed crossmembers between the trusses so you can't count on a clear path in the "attic" space. I removed the trim around the bathroom fan which gave me good hand space to manouver the cable. I cut a hole in the ceiling behind the microwave for another access point. I could not get a cable across the trailer for anything even though it looked fine. Then I removed a factory pancake light and used the little hole in the ceiling as an access point to fish the cable across.
Every make and model of RV is different and has it's unique challenges to installing new wire/cable. You have to put your thinking cap on and find creative ways to fish the cable around. You can get in/under a bathtub, kitchen cabinets, storage spaces, etc. Since you can't drill down a top plate in an exterior wall like in a house, you *could* install a cove molding to get it from the ceiling to wall.
Alternatively, you could go under the trailer in spots. If you have the black fabric underneath, there's repair tape you can get if you want to cut a small hole for access.