As good as my Nunatak overquilt is; it isn't warm enough.
I'm going to tackle another idea but I need some design help as I'm not sure how to handle the head area of a Gerry Cunningham "Mountain Sleeper"
The Mountain Sleeper is basically a top quilt with a full length pad sleeve sewn to it
RSbtR had some offcuts of APEX insulation very affordably priced so I will be layering 3.6# and 2.5# [ because that was what was cheap, 2 metres of 3.6# and 3.5 metres of 2.5# ] plus a small scrap of something thicker for the footbox
I have no real problem with the sleeve or the basics of the quilt itself.
I'm wondering how I will tackle the hood area tho
I'm also wondering whether I should use a single zipper on the easy side [the Left so I can use my right hand] or if I should use 2 zippers, one on either side and what fabrics to use on the bottom of the shell.
I have also asked this same question over at BPL because some of the members there are more familiar with deep cold conditions.
A layer of 3.6 plus a double layer of 2.5 over the torso should be good for a 20C boost in temperature rating