If you want to go first class, try www.veskimo.com. Pricey but it is like air conditioning.. If you're solo it's OK but two up, not a viable option so the other water evaporation vest would be the way to go. I've used one for years in the summer. You do have to add ice to the chest about every gas stop. And you'll need to wear a heavy coat to insulate yourself from the outside heat. If you can figure that.. It is the same system astronauts use to keep them cool while on the ground waiting.
I use Veskimo vest, I upgraded the cooler to a bigger size and I pretty much use the whole bag of ice and it lasts about 3 hours.