I have the insulated food pack from Kondos and a cooler that fits in it like a glove,  I made a freezer box out of styrofoam about a inch thick, big enough to finish filling out out pack.  We use dry ice in the freezer section and reular ice in the Cooler.  I can send pics later. or PM me for more information.  Works for our group as we have had stuff stay frozen into day 5 of an 8 day trip.