[talldudenumber5]

they have plug in 12 volt cooler at truck stops walmart etc. why not use one of those maybe take it apart and put it in line with your vents to help. you could run it to a 12v battery in the trunk. the battery in the trunk has a dedicated charger. when you are done driving plug it in to recharge the battery.( added benifit of people thinking you now own a plug in car) you could add solar panels to help out. you could also run a wire from your car battery to the dedicated ac battery and put it on a switch for emergency use.
the whole set up would not cost more than 100 dollars and thats if you have no supplies