I went with what Brandon "Warbonnet Guy" recommended and it is fantastic for me so far. Here is the web site http://www.foambymail.com/Minicel.html
and if you look down on the bottom is the MINICEL FOAM (3LB DENSITY) I bought the 1/4", 3/8" and 1/2" not having a clue what thickness would work for me. So far all I have used is the 3/8" and this past weekend it got down to 36 degrees and I was still just fine even being a cold sleeper. I got the 1/2 Sheet
27" x 80". They do get folds on the sides because of the curve of the hammock. I have thought about cutting V's down each side, but it really doesn't bother me at all.