Last night I cobbled together a hammock sock based on Just Jeff's instructions. Insultex faces the bottom and sides, loosely following the lines of a traditional fishing dory.
I made the bottom piece 3.5' long, and included a six inch wide tail from the bottom piece almost to the foot end. The head end was left open from the bottom piece to the end. I put IX insulation on the bottom and the sides. I used the Speer Bugnet Adjustable Nonstructural Ridgeline.
Results: the foot end was never cold, but the wind got into the head end and opened it up.
Change: I'm going to make the head end just like the foot end, and create an opening in the middle, similar to what I remember Fin had on his sock a year ago.