I made a wooden mount for the LCD TV I added to my trailer, but that's only because I had access to the wood and the woodworking shop.
First step is to figure out where to mount the TV. You will need to figure out where the 'studs' are. I don't remember how I did that, possibly a stud finder; otherwise 'knocking' or possibly even just seeing where the factory installed folding TV shelf was attached. Once you think you know where the studs are, use a very fine drill to make sure they are really there.
Most newer LCD tvs have a standard mounting pad, and you can get mounts 'anywhere' (Costco, Home Depot, Lowes and WalMart/Sam's Club would be where I would check first). Make sure the holes on the mount will match up with your 'studs'. If not, you may have to mount boards to the 'studs' and then the mount to the boards.
Choose a mount with the least amount of movement you can tolerate. If that is enough that it could move while driving, you might have to mount some kind of restraining straps or clamps.
John (40' 2004 Country Coach Inspire DP)