might try using the fans for neg pressure. (box fans have little power to do much from that distance.) Might even be better for positive pressure once you remove that front facing strip from the roof. Put the fans right below the opening not even need the insulation. and blow air upward towards...
Plywood might work, but it's expensive and heavy. I think the foam boarding is actually cheaper. Plus you can attach it to anything easily without worrying about collapse from weight
I would say that roof is the issue. If you could line it with anything, it would help. That foam board is fairly inexpensive. I believe it was less than $10 for a 4x8 sheet. I didn't read the exact thickness, but I think it only came in one size. You might take that front metal piece off at the...
We went to Home Depot and got some insulating styrofoam sheets (comes in 4x8 like plywood) fairly inexpensive, and put it inside our shed. Just doing the roof and back wall where the afternoon sun hit decreased the temp in there by 15 degrees and that was closed in completely with no ventilation.
Thank you :) She's so cute and such a mess, if you could see her from all sides, her tan grew in to where it looks like she's wearing a tan vest. very straight line around the bottom of the chest, and a thin white line down the front chest to look like a split in a vest.