I understand about needing extra counter space. I recently extended my kitchen counter . by adhering 2 foldable brackets to the kitchen/ sink wall. Then using a 3/4 board and screwing it to the brackets.
This extended the kitchen top to drain pots and pans , or a table next to our couch.
you can adhere the brackets to the side of the bed. Adding extra supports on the inside bed wall., were its not visible . Plus when not in use it can fold down. I wouldn’t try to adhere it to the camper wall. Who knows we’re the studs are. Hope this was useful.