I got a spare hatch to open up and see how a ventilation fan might be added. So on to the dissection: First grind off the rivet heads, photo 1 below. The thing is bigger than I realized, almost 3ft x 2ft.
Next photo, insulation! With shiny stuff! Who knew?
Next photo, More Insulation! Better than 3" all told. Wow, I'm gonna miss that.
Next photo, the inside of the inside cover. Room for 4, count 'em four 8" round fans. Yep I think that'll work.
I don't think it'll be necessary to cut the rivets to put the fans in, maybe put them in from the bottom or something, but the top is going to need a wind deflector of some kind.
Jim