Layers = warmth

Clothes-layers are flexible because you can wear them in the daytime too.

-- OR --

A second sleeping bag/quilt will keep you toasty.

I'd avoid anything that doesn't breathe. Those emergency blankets should be used for EMERGENCIES and not for daily use. If a 2-ounce blanket was truly comfortable for extended use, EVERYONE would be using them...all-the-time

ALSO: R factor on ground insulation is for-real. R-5.7 --> get it.