The only sure way to mount things to the thin interior walls is to put up a 3/4 inch flat board first and attach those four corners to the thin wall with MOLLY BOLTS... This spreads out the weight of the object to be mounted and hopefull will not allow the screws (bolts) to be pulled through the thin wall.

Custom fit the back board first..

Once your heavy back board is installed then you can just use regular wood screws to attach your LCD hardware to the wall. Your LCD installation might look something like this

After you install the back board first you can paint it to match your wall decor.
Lots of info on google search about this...
I have hung some pretty heavy items on my trailer walls using this method.
Also alot of the newer trailers already have a more solid wall just made for installing LCD monitor to the wall. They usually have a sticker on the wall that says Mount LCD Here or something to that effect. I would test it first however...
Roy Ken