You will find interminable discussions here and at hammockforums.net about staying warm. I strongly advise cutting through the b.s. and getting two micro-cell poly pads. The smaller the cells, the higher the r-value. Sometimes Walmart has good ones, sometimes not. Hammocks work better with full length and full width pads. Then cut 4 rectangles 10x16 from one of the pads. Keep the rest of that pad for torso insulation in Antarctic cold. Tuck the rectangles under your shoulders and anywhere else you feel a cold spot. This system is simple, inexpensive, fiddle free and effective. Or you could sink large bucks and lots of fiddle time in underquilts and such without gaining any more comfort, weight savings or trail time. Just my not so humble opinion, having tried it all and having lived in a hammock for close to 12 total months of trail nights in all weather.