Awesome post. And it's good to see another hunter-gatherer on here :).
And you got 100% of my Power (Not that it's much :D) for commiting to the challenge and also doing it before :).

What I might suggest for your husband is a "fat" fast. Basically it's the purge-fast I was reffering to in my post but didn't actually go into details as I didn't want to overwhelm people reading it. But a very quick rundown would be.
Thursday Dinner - Very low carb (so maybe your standard dinner :) )
Friday - wake up, get water, add salt (for minerals >> anti headache,cramping, etc.) and lemon juice (not sweetened). And go for a brisk walk. For few hours, four seem to be a magic number. The idea is that you get your body into ketosis faster. Then it won't need carbs that much. Also, (you can have it even before heading out) you can have pure fats (MCT Oil, Coconut oil, maybe potentially ghee but I don't have any self-experimented or scientific data on that so that's purely up to your consideration)during the fast, let's say in your coffee or tea. Caffeine also helps first day or second, too.
Also, BCAA should be very helpful for lean people with fast metabolism (as I'm too). But I didn't try it personally on myself. Though it'll help with muscle-retention.

Thanks for commenting on my Post, too :).

And congratz on being picked up by SteemTrail :).