......or take your two gal. milk container, fill 3/4s full with water and freeze, this allows for expansion. After that, they make good " stackable building blocks" in your cooler. As the guys above said, plus it all depends on what part of the country you come from.
As for me( being inCanada), I have no problem with worrying about getting my meat cold after the hunt. Usually about 15 minutes after we gut the animal, it is frozen, or at least REAL cold

Ron