If the freezer isn't full, you could fill up ziplocs/jugs with water, and then allow those to freeze. The fuller the freezer is with frozen stuff, the longer it will be able to stay frozen.
Some raw feeders that I know take their dogs camping with them. They freeze the dogs food in a bag, and put that bag in a bag full of water, and then will freeze it. The food stays good for a much longer time that way.