well you could test things out pretty easy. pack up the box with a digital thermometer, all my duel zone ones come with a min/max function, and do a trial run or 2. I'ld try it once at room temp and once in the freezer. Thist should give a good idea of the temp fluctuations. Also Ild run the tests 2-3 times longer than the actual shipping time cause "***** happens"
just my thoughts