Bottom Insulation - Wool?
Granted, you wouldn't want it for a long haul trek due to its weight but has anyone tried a wool blanket as bottom insulation in the same fashion you would lay on a pad? Or if you have some ability, you could try a wool UQ.
Like I said, its weight keeps it out of the pack for long hauls except for possible wool diehards. However, a wool blanket is pretty cheap and bulletproof. When wet it still provides something like 90% of its insulating value and it can multitask. Also it won't take a spark from a campfire unlike nylon that instantly light your butt up.
"The difference between genius and stupidity is that genius has its limits." - Albert Einstein