I've slept down to about -18C in a hammock. If you were comfortable at 20F, you may be fine at 8-10.

Ensure you hang your hammock low, with your tarp well covering it. Site yourself such that wind is minimized if possible.

In cold weather I use a silnylon poncho rigged under my hammock as an insulation holder/windblock - I then put stuff in there, space blankets and/or wally world insulation batting, or even another small sleeping bag. I then have a blue foam pad in the hammock. at -18 I was sleeping in a full fleece, with a toque and balaclava on.