I still need to sand the back wall metal. I found the diamond pattern was better accomplished by hand. The electric sander worked very well on the horizontal line pattern of the roof/sidewalls and the under bunk and front camper-box walls, but the diamond pattern segments (gold colored) on the sidewalls didn't get an effective sanding by using it.
So I'll get to that, but for now - I was in the mood for something else.
I had a general plan for that rear roof-vent tear, but I felt whatever fix I did would fail if it didn't have good support beneath it. Time to shore up that area under the metal.
From the factory, both vents had 1/4" plywood lifts to hold that part of the skin higher than the surrounding areas, to create a slope for water run-off? I guess that works theoretically, but in practice, because of the metal rigidity, I think it just lifts the metal 1/4" away from it's underlying support out beyond the lifted area. Could that have contributed to the tear? Here's a picture with one leg removed.
My plan includes "Reflectix" (1/4" thick foiled-faced and backed bubble-wrap) over the structure before the aluminum skin - as a replacement for the 1968 factory choice (about the ONLY choice back then) of thin duct wrap (1/4" fiberglass batt with vapor-barrier paper backing - similar to residential fiberglass batts in your wall cavities, but very thin - which incidentally, was the camper's ONLY insulation).
Due to the thickness of the bubble wrap, the aluminum will be held approximately 1/4" higher than the camper structure in a sort of cushioned lift. So my 1/4" vent framing boards will in essence create a level playing field for the roof metal edges around the vent openings.
I didn't like the original four leg design. So up front I had re-designed the boards to bridge the roof ribs and create what amounts to a full square piece of solid wood material. Except that I didn't have a scrap piece that big, so I made two u-shaped pieces that placed the two butt joints over two roof ribs, lending good support to the joints.
Now back to the rear vent, I measured for distance to place blocking underneath the tear in the metal. Then I did the same for all four corners of the vent area, so as to have balance for any final decisions on the repair covering (probably some sort of extruded aluminum plate acting either decoratively, functionally, or both), and ended up with this.
I glued the blocks in place and added weight for good pressure while drying. Those are bags o' tire-chains.
While the glue dried I set about making the plywood square. Now once again, I didn't have a large enough piece of scrap to make a single unit, so I used the two u-shaped piece design back here as well.
I stapled the boards in place.
In the above photo, the near corner on the right side is where the metal tear lives. It goes 3.5" straight back (right) from the exact corner, so it will now have ample support backing. And the Reflectix will come up to, and butt against, the plywood edge, not over it's top surface.
