I've read threads about improving warmth/r-value of sleeping mats. I have some of the ccf with silvered film both sides stuff. I'm easily able to keep it attached to the pad either on top or below with current sleeping bag that has system for attaching it to pad. So is it best, in terms of warmth improvement, to put it under the mat or between the mat and the sleeping bag? Yes I could try it both ways and find out for myself but I can ask you what you've found best without standing up from my office chair.