If you don't get a definitive answer, it should be easy to check. Set up the camper, remove a couple of screws from the lower trim on the shell. Examine the screws. Are there little bits of wood adhering to them, or are they shiny as if it just came out of aluminum? Now get a flashlight, and peek into the holes. You should be able to either see the wood or aluminum framing member. Then get an ice pick or something similar, and probe around the edge of the hole. The ice pick should dislodge some wood crumbs if there is wood present, or foam crumbs if the pick is encountering foam just inside the hole.
If you don't get a definitive answer at one hole, try another.
Bill