These are 20' lengths. Schedule 80 would be possible. My concern would be the rigidity of the schedule 80 applying more outward pressure at each rib. I have the same concern using 1 1/2" pvc. It's just a lot stiffer pipe. Schedule 80 is not as readily available in my community so I went with schedule 40. If the concern is snow load, I would be more likely to brace the structure from inside, rather than add stiffer material that may bow out the sides more than I want. Hope this helps Thanks for watching.
There are four t-posts that hold this up, fastened with plumbers strap. Sorry I didn't show that very well. The plastic connected to the endwall also helps it stand up. Thanks for watching.