humm,, I wonder if there would be a way to set the icebox so that it would exchange air with the cooler night air. Perhaps an air exchange at like 2am that will passivly cool the cooler to enforce a cool air temp during the day.

The issue with this is that the mass of the watter or any solid objects would not be cooled by the air exchange during the night. so no matter how cool the air is, the watter in the cooler won't get cool.

As I was reading this artical I was thinking about the colman cooler that is an acitve cooling system. This might work if you are able to afford the battery hit of something like that running off your car battery. This idea has potential to work, and potential to be brought to a whole new level of extreem.