Some unconventional methods that normally get used in other hotter countries- knitting ice into your hair, hang a wet cloth similar to Jenny but hang it around the vehicle, take a nap at the hottest point of the day (if you can do it), so on.
There was a story I had read once about a couple in Japan taking a Mazda minivan all over the country with newspaper cutting to avoid being caught by cops, search and see if that is useful.