Bill, you always manage to have a good harvest despite conditions that make many give up! I have learned a lot from you over the years, even though our growing areas are very different. You are a much harder worker than I am! As I get older, I find I can't tolerate hot sun as much, never used to bother me, though we rarely have the extreme heat and humidity you do. I thought about rigging up some kind of back/chest harness where I could suspend an umbrella above me to take my shade with me.
The best I can manage is to use a large portable beach umbrella when I'm able to work in one spot for a while. It's on metal tripod legs and easily pulls along the row with me.
It has a tilt feature that can help focus the shade where I need it.