The hillbilly aircon is not mine, its just an image of one off google, Im at work so cant post a pic atm. But they are common up here, most people use a good quality eskies and cut a hole in the lid as close to perfect as they can.
Even when the ice block melts some, its blowing off cold water......nice!
Never tried dry Ice for the aircon. Took dry ice on a camping trip once, but it really wasnt worth the effort.
Servos sell block ice here, and I have two car fridges, one freezer, one fridge, can make ice with one...
But really, just using the fan is ok most of the time.