I see you actually have 2 unlabeled switches.
One is probably for the front outlet on the doorside. That outlet has been around forever so you can hang lights on your awning or other places and switch them on and off from inside the coach.
The other is probably to switch power to light up your custom name sign that hangs on the front doorside. If you don't know about that sign, there's probably a form in the blue pouch full of manuals that came with your trailer.
Btw, we have a number of owner-written user guides including a user guide for the Landmark 365. It may answer questions you didn't know you had.
Here's a link.