I don't have a TV in my bedroom area but if I were looking I would consider these features:
24" typically have a 100mm x 100mm VESA pattern while 28" TVs start to go 200mm wide so you will need to consider that when choosing a TV mount. I just purchased a 28" LED TV for my Airstream and it has 200mm VESA pattern. The 24" model was 100mm. You can always purchase an adapter plate to increase up to 200mm. You would also want a tilting feature so you can angle the TV down a bit when laying in bed.
I would think mounts with the square backing plate would be better for an RV than mounts with a narrow mount.
A locking mechanism would be advisable. For additional piece of mind a Velcro strap can be used.
MorRyde has TV mounts for RVs
Small Extending Swivel Wall Mount
Of course you could contact Airstream to see what they use for bedrooms.