On a recent hammocking trip before Christmas I tested a wind barrier
for my hammock. I used my exta long poncho that I bought from
Campmor.com. I rigged the poncho under the hammock. In the morning,
after 15F temps, I noticed a little frost on the inside of the poncho.
I have some pics of this set up under Nate's Hammock.
I had a local seamstress modify my 20F synthetic sleeping bag to
include a foot zipper. This allows me to pass the hammock ropes
through my sleeping bag. I am completely surrounded by insulation
much like Speer's pea pod. Combine this with my poncho wind layer and
a fleece top and pants you will be quite warm.
Site selection is also helpful in any season. I have found that wind
sheltered areas are good for when its cold and less wind sheltered
areas a good when its hot.
Good luck and welcome to the group!