When mounting a LCD up high always find a mount arm that tilts up and and down as well as left to right.
Alot of LCD TV doesnt view well unless tilted down... My 22-24-26 inch VIZIO's is that way for sure...
I have also seen alot of high installs mounts work best if you put up a 3/4-inch large flat board on the wall first using a MOLLY type wall anchors in each corner or attaching the large wood piece to the thin wall studs somehow. Once the larger board is up then using regular wood screws into the 3/4-inch board to mount the LCD TV mount to... The trailer walls are very thin and you dont want the LCD TV mounts to pull out the screws from the wall.. One thing in your favor is the modern day TV don't weigh a whole lot like the older day ones did. You can paint the large mount board to match the trailer decor.
WALMART is a good source for different type of LCD WALL MOUNTS.
Just my thoughts
Roy Ken
