Here's some pictures of the attempt to salvage the overcab/bed
Tried a heat gun which helped but still wasn't great. Also tried mineral spirits which also wasn't very effective.
Took out the remaining screws, a little prying, and it came right out.
Got started with the rebuild, I matched the thickness and size of the old OSB that came out. The bed portion was 1/2", the first next piece 3/4" and the top piece 5/8" with a piece of luan so the trim piece would fit. I matched the angled cuts from the old pieces as well and also made templates of the sides of the camper where the overcab attaches. The templates allowed me to clamp the new pieces while the glue dried. In addition to titebond 3 i used some pocket hole screws to hold everything together. Since I was going to glass the bottom, I wanted to fill all the knots, gaps, and pocket holes with epoxy that I thickened with micro balloons and cabosil. I also added some of this paste to where bed attaches to the first angled piece since they didn't mate up very well.
After some sanding I glassed it with 6oz glass with a pretty big overlap in the center. I just used some old surfboard epoxy resin which is basically the same as marine resin.
I then sanded the edge of the overlap and any other high spots. Hot coat was next to fill in the weave which once it cured I sanded with 120 grit. I also painted on some epoxy on the exposed plywood edges to seal them. Next up was epoxy primer which I went with a two part marine primer by interlux
https://www.fisheriessupply.com/interlux-epoxy-barrier-kote-404-414-primer-kits
I'll probably paint it later once I'm ready to paint the rest of the camper. Not sure if I want to go with bedliner, marine paint, or just some exterior paint like rustoleum.
Roof prep has started, I spliced the 3/4" plywood together for the long side pieces and got the foam. I'll pick up the aluminum square tube next week and start building.