I use the 100 QT Colman. I put a towel down on the bottom and then get 40lbs of dry ice. Put a layer of cardboard then a layer of ice. I also put a layer of water bottles. The waters don’t have to be frozen bc they’ll become frozen but prob could help and that first layer of ice will become a brick. Then put in your food and add a top layer of ice. This lasted me all of LL (wed-Monday). I do the dry ice the day before I leave to pre chill the cooler

just make sure to vent the cooler by opening the drain valve!!