I have used a Hennessy Hammock Backpacker Ultralight with the Supershelter insulation system on 3 tours in February in the south/southwest US and California. The coldest night was 25 degrees F and I stayed relatively comfy. True, there are not always trees...just need to be creative. Sometimes I wish I had a tent I could hang out in. On the other hand, I probably get going earlier in the morning. The journals are here.
http://www.crazyguyonabike.com/direc...ser=Powers&v=B