As noted, Many RV's already have 'em factory installed.
Mine did not.. But if you have the connections (Mine DID not, does now) you can mount it most anyway.
In my case I have 3 Flat Screens, one is a "portable" the other two are mounted. I can simply take the portable outside and set it up.. Either in the bay, or near the bay Just take it in at night.
Home is where I park it!