Don't laugh. Bayouh makes a good point. I was going to suggest a small cooler, the kind big enough for 2 6-packs of soda, and one of those "gel freeze" things. The self contained gel types you throw in the freezer and freeze it overnight. It may condensate, so wrap the gel freeze bag in a hand towel, THEN put it in a 1 gal. zip lock bag(room temp). But the cooler if it's of good quality might insulate the contents well enough to not need the gel freeze bag.
Just a thought.
I have thought about doing something like this just because it can get really hot in car's. Im not sure what the cook off temp is for rounds but I dont want to press my luck. I can just imagin sitting in my truck with little beams of light coming from the top!!
