We made a quilt that he puts into the hammock instead of under. It is made out of polar fleece and 1"thick dacron filling. He folds it in half and lays on top of it. It gives him 4 layers of fleece and 2"of dacron. I know that he is compressing it but that hasn'"t been a problem. We are careful to sut up so that we are blocking that wind with the tarp as much as possible. I use jut a ez pad with 2 wool blanket folded in half and wrapped around the pad.
This has worked for us so far. We aren't new to winter camping and very cold temps, just new to the whole hammock thing. AND WE LOVE IT!!!
Time alone in the woods recharges my battery