You will probably get more warmth in the cold from additional pads than from lofting insulation underneath you. My memory is that the blue foam pads are between R2 and R3 and that you need at least R5 under you for frozen ground. My winter pad set up is a full length 1.5" Thermarest (the uncored kind) over a Ridgerest for R value over 7. Last winter, I realized it was finally time to throw away my old CCF pad because I was getting cold from the ground even with the Thermarest.