I got the tv mounted on our 2011 Shamrock 21SS. I did not want to screw the mount into the outer wall due to the t then hanging too far into the bunk end when it is closed and didn't feel comfertable bracing the entertainment center where the DVD player is mounted. When loading a Scrap trailer at work I found a box full of machine mounts that looked perfect for what I wanted. I only got 2 of them and will hang on to the other if I ever find another use for it.
The mounting plate had a pipe welded to it in 2 small spots so I welded it the rest of the way around, and it had a "hanger" that mounts to the pipe and extends another pipe with a plate welded on it to mount the machine. I used this for support and to lock the TV in place when traveling, just welded a piece of angle to the plate and added some foam for padding. I sprayed it Aluminum color to match the tv mount. The articulating mount works very well and we can now aim the TV into the bunk or even turn it to the door and watch TV outside if we decided to. Here are some other pics.
The piece to lock the TV in place for travel
Front view when locked