Hmmm. It seems like there should be a work-around somehow.
We did the stocked-duffel-bag routine and it worked out fine. We had the dining plan, so the only meal in question was breakfast, and I just packed boxes of cereal (which DS eats plain) and some gfcf breakfast bars. I packed breakfast for the rest of us, too, so he wasn't singled out. I packed snacks-- and remember you'll need snacks when you're travelling so some need to be accessible-- but he didn't eat a whole lot of those. There was a big bag of pretzels and he ate out of that for at least 3 days, the dining plan serves big meals and he just didn't need the snacks.
The milk- can he just go without? Or is it part of his routine? I have seen Very Vanilla Silk in regular grocery stores, even the
WalMart here carries it, so you wouldn't necessarily need a health food store for that.
Are you flying? I'm guessing you are, since if you're driving you could just pack a cooler and you wouldn't be using ME. Instead of "pack a duffel bag" you could do "pack a cooler", the smallest you could get away with while still packing what you need, and put in a ton of ice packs and check it. When we flew, DS had medication that needed to be refrigerated, I carried it on in an insulated lunch box with two ice packs, and it did just fine. I just made sure I didn't put it in there until we were on our way out the door, and I got it into the fridge in our room ASAP.
(which the fridge wasn't in our room at check-in and it was about an hour later before we got it, all in all the meds were in the lunch box for about 8 hours and were still cold)
I am thinking, and I could be wrong, that if you took one of the loaves of the frozen bread, put an ice pack with it, wrapped them together in a towel, and then that went into a cooler, that you'd be able to get there with it okay. You'd be chancing it more with the milk because of the possibility of it leaking- although- can you freeze the milk? I haven't tried to freeze soy before, you could try it now and see if it works. You could freeze it and put that in the cooler and I don't think it would completely thaw before your arrival.
Taking a cooler means you'd "lose" one piece of your luggage allowance, or you'd have to pay extra for it. But even if you had to pay $25 to check the cooler, it would still be cheaper than cabbing around Orlando.