Keep in mind you may have to add a 3/4-inch solid board to the wall first and then attach your TV arm to the board. The RV walls are pretty thin and may not support much weight.
This idea is used by alot of folks to support the moving arm. You can paint the board to fit your wall decor...
I like the idea one post did where you can remove the arm center piece and take the wall mounted HDTV from the wall very easy for storage when in travel mode if you think you need to do that.
photo from google images