We've had fantastic results with lightweight canvas socks in deep cold conditions (below 15*F). They are wind proof and vapor permeable, such that water vapor passes through without condensing. The canvas sock works just like an Anorak.
Last February, on top of Roan High Knob at 0*F, with 20-40 mph gusts, I was toasty with no tarp, and just a Snugfit and a Speer Top Blanket inside my canvas hammock sock.
"We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin