I've been dealing with this for 10 summers now. The best way I've found to keep cool is hydrate hydrate hydrate, and more hydration.
Short shorts and thin shirts. Also critical is misting water on any exposed skin including legs. Evaporation has a cooling effect. (why you get cold when toweling off after a shower) My mom always buys me those novelty misters with the fan on top.
I like where your head is at in trying to use technology to solve your problem. It could also be easily adapted to be a warming vest.
But don't forget the tried and true methods: replacing your body's sweat with misted water. Like every couple of minutes. It has helped me to tolerate a lot of heated situations. Good luck!