@mcallough There are wall anchors made for hollow walls that may help.
Some are a toggle bolt where there is a ridged wing(s) that will spread out on the inside of the wall.
There are anchors that you insert in a hole and then tighten a screw and it has a cage that then bends behind the wall. Once compressed all the way you can remove the screw and reinsert as you need to.
You might be able to use well nuts, these are a metal sleeve and a rubber insert that when screwed down will expand to hold. These would probably be the weakest method.
Screws with the plastic inserts I wouldn't use, they just don't hold well enough. Someone used these to hold a flip up table and small bar to the wall in our MH and over time they have come loose.
Might have to mount a larger piece of wood to the wall, then mount the tv bracket to that. Best would be if the wood was mounted into two studs (one on either end). Studs in most rv's are pretty easy to find.