I use these anchors in the camper. You can buy them in plastic or metal and there are several sizes at both lowes and home depot.
You drill a pilot hole and then drill the piece into the wall with a screw driver drill, then use the screw that comes with it. You can paint these when you sell the camper so there are no holes showing.
https://www.lowes.com/pd/E-Z-Ancor-5...cluded/1042133