Like everything else, I have jumped into this with both feet and am constantly looking for new things or different usages. Thought I'd share a couple.
The down side of mason line from what I have read is the color, usually pink or bright yellow. I am pretty sure the braided trot line in the fishing section of WM is the same thing and it's OD green. It is rated at around 150# test, if I recall correctly. This is what I am using right now. For those of you who like a splicing challenge (you know who you are), something to try, just need a smaller doll needle or piece of folded wire.
Has anyone tried or considered using hardwood flooring underlayment foam? It comes in big rolls and I imagine scrap could be picked up from an installer for free. It's thin 1/16"??, so probably comforms more and you could add layers to get to the desired thickness for moderate weather camping.