Diane sent me an email asking what I thought about using dry ice and/or freezing food before hand? My reply:

"Using dry ice in your cooler is a great idea, if you can get it. Here's another tip: wrap the dry ice in a few layers of newspaper and place it on top of the food. You can place regular ice below, and the dry ice will last longer, if you don't let it come in contact with any water. Freezing foods before a trip is also a great way to conserve ice in your cooler." ~ David

More about prolonging ice in your cooler

Tips for storing food at the campground