I spent years snow camping and we’d stand on foam sit pads to insulate us from the cold. worked wonders.

https://www.amazon.com/Therm-Rest-Cushion-Insulated-Sitting/dp/B01MRSVOP1/ref=asc_df_B01MRSVOP1/?tag=hyprod-20&linkCode=df0&hvadid=194852051030&hvpos=&hvnetw=g&hvrand=15134243592625899350&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9005931&hvtargid=pla-315750873295&psc=1

but just the plain cheapie blue ones you buy and cut yourself at a army/navy store works just as well. recommend!