I suppose it depends how heavy he's willing to go on food. You can get pretty good freeze-dried veggies these days, even from the grocery store. The "Just" veggies are what I'm talking about. Just Tomatoes, Just Peas, Just Veggies, Just Raspberries, Just Bananas etc. You can order them online, too. A little goes a long way. You can take fresh vegetables, too. Broccoli keeps pretty well. If you tear up Swiss chard leaves and put them into plastic bags with a sprinkling of water they'll last a couple days. Dried mushrooms from the Asian grocery stores are great. Also look for various kinds of rice "stick" noodles.
You can get a product called "creamed coconut" which is like a brick of dehydrated coconut milk. Make a curry with it. It's very high in fat and tasty. You could probably do things with coconut butter, but I'm not sure what. I made it into these little "candy" type things by melting it with dark chocolate and pouring into muffin tins with nuts. They melted way too easily (even though it was November in Southern California and the trail had snow on it) and were a mess to eat.
There's always the old standby stuff like jerky, dry salami, cheeses (real aged gouda or parmesan seems to carry well), nuts, dried fruit, that sort of stuff.
You may also like to look at Dicentra's website to get ideas. Perhaps you can primalize some of them.
Home - One Pan Wonders
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Current squat: 180 x 2. Current Deadlift: 230 x 2