So I finally broke down and I bought the PL from my local surplus store, and although I paid a little more for it than I intended to, I feel that this was worth it. It was a brand new one made of a 100% ripstop nylon shell and 100% polyester fill. It also came with a ripstop nylon stuff sack, from which I carefully removed the plastic sleeve. I also removed the care tag from the liner itself. After that, and before all the hardware, it weighs in at a whopping 594g, so JUST under 21oz. I'm enjoying the weight savings and I tested it as a the other night with pretty nice results.

Next I will go get some shock cord and cord locks and turn this into a new-sew summer UQ!