Howdy "Rollintent"
I had a issue with offgassing with my trailer aswell for the first half of the year. It was so bad in the summer last year that i could not spend a night comfortably. Hi temps didn't help either, With day time temps in the 90's. Inside temps were oven like at 120' or more!

So far to fix the issue i have, installed a roof vent with cover, Painted the roof white, Installed a 15x24 window and last but not least I painted the inner walls with water based paint to seal the fumes away . Painting the walls along with summers heat have baked the fumes out to the point were you barely notice anything. I know paint isn't the best looking but I didn't want to spend so much on adding dead weight and cost to my build. That and the fact that most of the faux paneling on the market will offgas more junk than the plywood.

IMO
Best of luck on your build
