and I thought if it works for a tarp, why not a pack, except I wouldn't need the heat reflective stuff for a pack. Is there any particular pattern you would recommend as a good starting place?
I'm going to say that's not a good choice of material for a pack. I've got a campfire tent I made with that stuff, and while you can keep the load on the tape when pitching the tent or a tarp, the material will not carry a load like that of a pack. It will tear at the edges of the tape seams. Works great for a tarp or tent though, and the campfire tent is incredible. (campfire tent)
I made a pack out of feed sacks that worked really good. I used nylon webbing to strap it to an aluminum frame but you could sew up a harness with the webbing to make it a frameless pack easy enough. (feedsack backpack)
As for staying warm, I use a piece of bubble foil insulation on top of my pad. It will work great with your CCF pad too, and if you know a home contractor you can probably barter a piece from them for a beer or two