OK, this sounds crazy but experience is the teacher. I (69yr young) work 23+ acers of wild land I am slowly building a family off-grid homestead food forest on.
I have learned to cover up and wear a wide brim straw hat and one of those wet cooling clothes to cover the neck. I wear loose fitting sweatpants, and loose fitting long sleeve shirt.
I am in South East Alabama and summer is hot and humid. I am totally soaked in sweat in just a few working minutes no matter what I wear. The sweats and shirt soak up and evaporate creating a bit of cooling effect. Protects me from mosquitos and briors.
Looks very hot to wear but not as bad as you think. I am actually much hotter in shorts and tee shirt than in the full getup. Works especially well if there is even a slight breeze.
Give it a try.