Great thread, thank you!
We always used a lean to in the southeast due to lack of crazy cold and the need to have a little air flow to cut down on skeeters. Usually coupled with a small "smudge" fire in the night to try to keep skeeters off.
However in cold weather this setup SUCKED and you either had to have a helluva roaring fire or enclose the front and leave the fire out- essentially making a debris hut like you mentioned.