In addition to the air conditioner, you'll also need to get the "ceiling assembly", which is that separate part that you see inside the camper. Some are made with the controls, thermostat, on-off switch right on them so no need for a thermostat on the wall. However, if you are in a 5er and the ceiling is high, you might not be able to reach the controls.
Either way, you'll need to get the ceiling assembly too that matches the air conditioner you get, and the air conditioner will need to match your existing ducts. If push comes to shove, you can always run a wire outside your walls and cover it with trim, and then put a wall thermostat anywhere you want.