Alan, I've gone through the mill with trying to decrease the gap on roll-off's and domes, roof to wall. The best way I could determine, and I'm confident, was to employ a flexible "brush" type seal. Whilst not completely airtight, it would be dense enough to prevent ambient air blowing through the gap, and getting rid of the worst of the wasp/spider ingress.
https://www.truckandtrailerpartsonli...ush-100mm~1146
This type of brush is ideal for forming around uneven or non parallel surfaces.
I've since opted for an insulated and dehumidified warm room, adjacent to my "pier garden", as I have several scopes.