I use my Coleman XTreme for tailgating. Throw of layer of ice on the bottom, and put my food in ziploc bags or those cheapo plastic containers. Then sprinkle ice in from the top, filling the gaps.
It melts, but you don't care since your food is protected. Sometimes in my smaller coolers I'll put the ice in a ziploc bag, and not the food. But I don't think that provides as effective cooling.
18.5" WSM ; 22" Kettle ; Weber E-330 ; Weber Q200 (for tailgating)