On a trip last month I noticed the engine door was not closing fully on the passenger/ladder side. It ended up that the latch had 90% pulled out of the door. A bungie cord and a few tie wraps and we were fine to travel home.
Upon inspection the mounting surface on the door was spongy. I cut the surface fiberglass off and found the plywood core to be completely dry rotted out. The majority of the core I could pick out with the tip of the screwdriver. I think it was a combination of the ladder bracket screw on the outside and the door latch bracket screws on the inside where the water intrusion occurred.
I left a bit of a flange surface of the existing fiberglass and cut a new core plywood piece to fit. I ended up cutting the piece into 3 puzzle like pieces so they could fit in but be larger than the opening. I sealed the edges of the plywood with epoxy and glued it into place with epoxy and filler. The next day I glassed it in with epoxy and multiple layers of 1708 fabric. I gave it a couple of days before I drilled and used stainless screws to attach the latch. I did use a dip of 3m marine adhesive on each screw to prevent it from occurring again.
I will likely do the same repair on the drivers side as a quick check found 3 screws tight but one loose. The 1708 is a bit heavy. I may pick up some lighter fiberglass cloth for the final layer and extend a few inches further, revisiting this passenger side again also. Its a good reminder that any exterior screw on our coaches is an opportunity for water intrusion.