You know, you just gave me a great idea.
Have you ever felted wool?
It's EASY to do and so lightweight it's amazing.
I bet a person could wetfelt a pad that would be killer for use in the hammock!
Lightweight and VERY good insulation ... I just might have to try it!
The other thing a person could do is buy an old wool blanket at a yard sale.
Then toss it in the washer with HOT water, then into the dryer.
Then just cut it to size.
I bet it would work great as a pad!