I bought one from
http://www.levelmount.com/
for out on my patio in the backyard. I also bought an extra mount for inside the house in one of our yet to be converted into a den type of rooms. The one I got was for a 40 inch lcd. It is a beefy sucker. But an excellent mount.
The part that mounts to the wall for ours for a bigger tv is like 2 inchs by 5 inchs or something like that, so not huge. I have one mounted on the brick of the house in the patio are and one on the wall inside the house. I could literally hang off either and nothing at all would happen, they are that solid. One little button to push back at the top and the whole swingarm and tv comes off the mount...then we bring it outside and put it on the mount there..takes about 2 minutes.
Now if you can find one in the size you need and find a solid attachment point, I don't think you can go wrong. Not sure how it relates to an RV but I think they have a warranty that will replace your tv up to a certain amount if the system fails and the tv is broken.
Edit: the one that is for the outside that is exposed to the elements is still holding up great, I don't think there is any rust on it or anything, and this is in michigan over about the last 3 or 4 years..