Bill, are you using Reflectix? I use it for specific insulating projects and radiant heat in construction. I've never tried it DUH!!!!!!! thinking it would not stand up to being rolled on as a floor. If it works for you, I'll have to get a piece and roll it up and attach it to the outside of my pack. I know my circulation is on the downhill slide as I get older. Making shelters with some warmth in them is very encouraging to keep doing the things you love. Cool post.