Well, here's my first hang-in-cold-weather story for ya!
Last night, I just couldn't stop the itch. It was cold outside, and I just couldn't stand sleeping in my bed. I bundled up and went outside and set up my BB and tarp. I don't have an UQ or a sleeping pad. I just have an old Coleman mummy bag that weighs probably 3 lbs.
So how did I stay warm? An old blanket. I lined my hammock with this thick, heavy blanket, and put my mummy on top of that. Crawled in and slept like a baby till I woke up at 2 in the morning. I never got too cold, but I couldn't fall back to sleep after I woke up, which was a disappointment. I did lay there, though, and enjoyed the serenity of the cool air and quiet that the night provided.
Knowing I had to work all day today, I lamely crawled back in the house and slept for a few more hours.
With these kind of experiments, I see how important it is to have good insulation when you sleep out in a hammock. Sleeping on a blanket and a sleeping bag inside was comfortable, but irritating at times, definitely an issue that can be resolved with a sound underquilt.