Given your....er..."jumbo size", Blast, let me suggest what's worked for me. Many fabric stores (in my case Hancock Fabrics, a national chain).. but I've seen them on the internet too.. sell 100% polyester fleece for $6.00 or less per yard (at a 58-60" width). I got a couple at 2.5 yards, and use them all of the time when camping: alone, or as an extra layer in my sleeping bag when it's too cold.

I've found various thicknesses, but for me the thinest was warm enough for spring and early fall camping. I cut a slit in a shorter piece (1.5yds) and use it as a poncho or a blanket, too.