when i have frozen meat delivered it comes in a polystyrene box.also in the box are some ice cube bag shaped frozen stips that contain a substance that, when it defrosts turns into a hard pellet that can then be re hydrated and frozen to be used again.The meat stays totally frozen even if you leave it in the box all day.or you could look at these,see if they can help you, good luck :-)
http://www.pedtech.co.uk/thermotainer/pages/th ermexx.htm
http://ferribox.co.uk/fabricated/fabricated.ht m?gclid=CIC2-qLI_pYCFRHdlAodOliNYw