I have almost that exact floorplan and put the TV there too. A few simple steps. First, a 1x4 of ash is cut to length so it fits snuggly between the bed and upper cabinet. Then I stained and finished the board to match.
Next I mounted the TV mount securely to the board.
The board is then snugged into place between the bed and the cabinet bottom and two screws - one angled into the bed wood and the other into the cabinet frame now secure the 1x4 to the RV.
Nothing is glued or drilled up much. The board and TV mount can be easily removed and two screw holes filled.
I can post pictures if you want them.