Steve, This is an excellent topic for thought!

Thanks for bringing it up!
Out here, in sunny California, we don't think of it too much as many of us don't go camping when the weather is c-c-cold. However, one never knows when a trip over the mountains might be necessary.
MaryC is right when she says that it is best to stay away from foods canned in glass jars. I wouldn't want to clean up a mess like pickle juice either...especially sweet pickle juice. Ewwww! What a mess that would be!
Redgloves had a good idea, with using a light to keep things warm enough. However, to clarify that, it should be an incandescent bulb. LED's won't work at all. (Most people know this; but, ya never know who might not.) I don't know if a fluorescent bulb would work; but, due to what happens when they break, I don't think I'd try it. (I've never seen fluorescent bulbs used to keep water pumps and pipes warm but they do use incandescent bulbs for that purpose.) Out here, we use the old fashioned incandescent Christmas house lights on citrus trees, to keep them from freezing on cold nights. If you happen to have any of those stored away in your attic or basement, you could string them around your food. However, you might get some strange looks as you motor down the highway!
BobHenry also had a good idea, using an ice chest; but, if you don't want to hunt up an old one or run out and buy one, you could line a cardboard box with Styrofoam, especially if you have some left-over pieces in the garage. Line the box's bottom, sides, and top with the equivalent depth of 2". Then, for added measure, wrap the box in a blanket and put your towels and clothes (ie. dufflebags?) around it.
If you are buying water in bottles, and they don't already have an air space at the top, I would suggest emptying a little out, because water expands when it freezes. If you are filling water jugs, leave a little bit of air space near the top.
Your best bet is dried food because it will survive just about any temperature; plus, it is easy to prepare and makes a hot meal in a hurry. Even if you are taking cans, I would put a few freeze-dried meals in the mix, just in case. Those scrambled egg packets, fixed with hot water are mighty nice when the morning is the coldest and you're jumping around, trying to keep warm.