I finally put a big hole in the camper to make the storage area under the rear bunk more usable. So first the template was traced out on cardboard. Make sure you label it to keep the sides from switching. This is with the template positioned inside. Wires had to be raised to prevent damage during the cut. I decided to go as high as I could to leave some side support at the bottom of the hole. It also prevents stuff from from falling out when door is opened. Since I was cutting a big hole, I decided to add some structure to the sides. I marked 2 spots on the template and drilled holes to the outside. Drill bits were placed in the holes to position the template on the outside. Template was marked on camper and then taped. This prevents marking up the camper with the jig saw. Use a vacuum while cutting because the Styrofoam inside camper wall goes everywhere. I used an oscillating saw to fine tune the opening to the door frame. I made sure I covered the exposed Styrofoam with sealant. Put a good bead of sealant on door and around opening. Install door and smooth / remove excess sealant. Door was clamped in place for half a day. Door latch was installed above door to hold open. Inside structure was bench fitted and attached to camper frame. Being a mechanic, I couldn't just glue it in. I added fasteners going into the added structure around the frame.