Met a guy in Louisiana, middle of July, bundled up with a puffy vest and leather jacket over top. Got to talking with him...
Turns out he is very heat sensitive and wears a cooling vest. His vest has water chambers running through it, hooked by a tube to a small cooler full of ice water he had in a bag on his passenger pad. Every stop he lifts the cooler lower than the vest to let the warm water out, sloshes the cooler water around, then lifts the cooler higher than the vest so fresh ice water runs into the vest.
Kinda like if you've had a surgery and they have those joint wraps hooked up to an ice cooler.
He was all bundled up to keep the cold in. Says one cooler full of ice water lasts him all day.
For the life of me, neither of us can remember what brand he said it was.
Hope this points you in a new direction to look...