RoyB does not know how your trailer is hooked up as he does not use satellite and has not in many years.
Your coach is wired specifically for satellite and it absolutely CAN be used to connect your satellite antenna. It is a dedicated line that runs from outside to inside with no other connections or splitters involved.
Additionally, someone mentioned copper clad coax. That will not have any effect on the satellite connection either at the short distances involved here.
I would start by working backward. Start by connecting the receiver to the TV while inside and verify that you are able to get a clear picture from the receiver to the TV (no snow) even though all you will see is the Dish Logo bouncing around. If you can get that, connect the TV with the same coax to the inside port that should read Satellite and then connect the receiver to the outside satellite connection and you should again see a perfectly clear bouncing Dish logo. If that does not happen the coax cables may be reversed or mis-wired from the factory. Try the other connection just for grins. If none of that gives you the clear picture you should get then it's most likely that just the end connectors of the cable need to be replaced but if fixing those does not fix the picture the manufacturer may have run a staple through (or cut) the coax somewhere. If that's the case you are going to need a new cable. Worst case you can temp. run a coax through the slide seal or a window to the receiver and connect the receiver to the TV so you can get your satellite until you can get the cable fixed or replaced.