Most likely you should mount a nailer (say 1/2" or 3/4" plywood, etc.) that spans between two studs in the wall. Then, mount the TV bracket to the nailer. Don't forget to strap the TV when you want to drive.
In our motorhome, we have aluminum studs - pretty traditional around windows and then floor to ceiling - a stud finder works in our unit.
If using plywood, I'd suggest marking for the mounting plate on the plywood, drilling holes and using carriage bolts from the back so that you can put lock nuts on the exposed bolts once the plywood is mounted.
Many TV mounts provide horizontal brackets that can overlap two studs - thus eliminating the need for the nailer/mounting board.