Thinner is good, ask DJ Short. More UV. I'm in Colorado, I understand the strong sun and sun glasses. Up here you get sun burn easy even on cold days.
33 in aug? wow. how many hours of day light? Here it hit 28-29F on set 10th last year. Froze out a lot of corn. The last 2 years ,mothers day, may 15th, it was snowing this year with hard frost. No early garden.
You sound like a smart fellow you have some good hope for pulling something amazing off up there!
You plants look great for what you are dealing with. Some good smoke to sit the winter out.