Well, I'll start out by apologizing to any Apaches that may be present for my inadvertent rudeness. As an act of good faith I'll even go so far as to forgive you for implying that I was a "brownie" just because I live in NJ, have the same first name, have read some of his books and like to stay warm in cold weather. I don't even own a loincloth.
Chapter 3, page 38, paragraph 4 of all survival manuals shows an illustration of a lean-to with a reflector fire in front of it. You'll notice they never show the survivor in the lean-to. He's off gathering more firewood (again).
The point I was trying to make is that there were a few situations when he probably would have gotten some sleep if he had put the same effort into an enclosed shelter rather than something more photogenic.