Cold is relative too-take that into consideration. The Gossamer Gear hammock pad I have took me into the low 40's (some say it got into the high 30s, but I was sleeping
), with no issues at all. BUT, again, this pad is WIDE-so, it wrapped around my body. And, I was inside a sleeping bag.
Pad dynamics change when they arent on the ground-first, the heat transfer is different. Second, larger CCF pads are more for comfort from the ground-not so much insulation. You will feel roots, rocks, etc, much more easily through a 1/8" pad than you would a 3/4" one.
Heat transfer MAY be negligible though (I dont know, and never even looked into it, but it would make sense, as CCF will crush to a certain point under weight). I would think that heat transfer in a hammock may be different-you MAY be able to get a higher temp rating with a thinner pad.
The compression would be slightly less (ground is hard, hammock bottom more forgiving), and it would come down to simply something like you move off the pad at night, and encounter a cold spot. Other than that, I think that a pad of adequate width would work just fine during 3 out of 4 seasons. This is based on MY experience though. I have slept in sub zero weather, on the ground,
with only a CCF pad under me, and I was fine-that experience alone tells me that the pads insulative properties worked fine, even when crushed under me. The pad was a standard military issue one-maybe 1/4" or so. So long as I stay ON the pad, I am fine. Come off the pad, I got cold, fast. I would assume the same thing in the hammock.