Reddit mentions of Polar Tech IB6 Ice Brix Leakproof Viscous Gel Refrigerant Poly Pack, 4" Length x 6" Width x 3/4" Thick (Case of 48)

Hmm. That is tough. Canned/pouched chicken, salmon and tuna. Do you like sardines? Excellent source of protein and calcium. Canned beans, chicken/beef broth, canned chilies, even some cans of commercial pre-made chili can be ok, especially if you watch the labels for sugar content. You might try canned veggies like green beans, lima beans, sometimes you can find canned collards, spinach or greens depending on the area, sliced and canned mushrooms too.

Dried onion, garlic powder, oregano, salt, pepper, hot sauce, herbs and the like are going to be your friend if you are cooking via microwave or crockpot.

A cooler with some heartier veggies like broccoli, cabbage, brussels, kale, zucchini, peppers, onions and the like would probably stay fresh for several days at a time especially since most of those veggies would be ok outside of the fridge. Ice packs like these are excellent for keeping things cold for awhile: http://www.amazon.com/Polar-Tech-Leakproof-Viscous-Refrigerant/dp/B008K9609I/ref=pd_sim_hg_7?ie=UTF8&refRID=0QW1Z2NTDWXHYPVGMSV7

You might want to google low-carb camping or backpacking for ideas, and check out this thread:
http://www.reddit.com/r/keto/comments/1bztel/low_carb_campingbackpacking_foods/