Some setups use a swivel mount so that the TV can rotate a bit to be able to see it better from the sofa in the slide. You may not need an articulating mount. With a swivel type, you'd have no worries about what you are fastening to on the wall behind the TV.
Take a look at Moview® flat panel Mounting Solutions
for the locking type of articulating mounts. There is also another place to buy locking RV mounts too but can't remember at the moment. CW has a locking type, but I highly recommend against it for quality reasons. We bought one and could not use it was so bad. Ended up buying a twin arm one from TV Mounting and Video Security Solutions
and are very happy. Also used 1" Velcro.
If you go with an articulating mount, you can use any one out there and secure it with Velcro straps for travelling. An articulating mount is going to be around 10 lbs and the TV maybe another 20 lbs or so. And with an articulating mount, if it is fully extended, that's a lot of extra force pulling at the screws on the wall so you want to make sure you have the mount well attached to something "structural".