@pushing_tin only one correct option here! The MORryde TV1-025H wall mount:
When you say “new to us” do you mean you purchased the trailer used? Because when it is new you normally have a sticker where the backing plate is installed. I don’t know specifically on your trailer but behind the wall where your outlet is, if you use a magnet you can “feel” where the edge of the backing plate is located.
The way I have installed this is I run the magnet around the plate to get the full dimensions with a pencil. Then what I do is cut a piece of cardboard the exact size of the TV screen. Next I mark the location of the mounting holes and then tape the cardboard to the mount. Alternatively if your TV is not heavy you can just mount the TV but next step you will be holding it up and that can be heavy after a while.
With the cardboard mounted, I hold the mount up the wall to get a idea where we want to place the TV so it folds flat against the wall and clears any window treatments, doors, etc. Then you can mark the holes with the pencil and finally drill smaller and screw in the screws for the mount.
I don’t like to use a drill because I want to fell the moment the screws tighten up but before you strip any threads you just made.
Now mount the TV if you haven’t and enjoy!