I’ve done a few multi-day winter trips with a 10 lb base weight (aka 10.10 and 10.63, but who’s counting). The thermometer on my watch stops working below 14-15 degrees so I’m not sure the exact low temps but I’ve slept through several nights after my watch froze. I would feel comfortable taking this setup down to 0 for a few reasons:
On most nights I sleep without a puffy and although the Montbell Mirage or EX Light are included on the lists I usually just bring the Blackrock vest. I use the lightest stable winter shelter I could find so that I could ‘spend’ the weight on extra 900 fp down for my quilt. In my experience a lightweight cuben MLD Solomid made with 0.5 oz/sqyd cuben holds up well in (very) high winds and weighs just slightly over 8 ozs. I end up using more down (16.7 ozs) for my quilt and I have slept warm through a some all night storms. Also, to save weight I engineered the footbox to fit the shape of my feet and included a little extra room for homemade down booties. For perspective I’m 6′ & 195 lbs in the winter:). More info here:
Winter Quilt with Trapezoidal Baffled Footbox
After my Monatauk Gnat canister stove failed last spring I broke down and finally starting using an old heavy Whisperlite w/ a Trail Designs ti windscreen and Evernew 1 liter pot/lid. This is plenty for me and one other person.
A few other key pieces of gear have been the Suluk46 ti snow anchors (.5 oz), Blackrock down mitts (2 ozs) and beanie (.8 oz), Snowclaw shovel (6 ozs), Rocky Gortex socks and some homemade stuff like w/b cuben/dyneema glove shells (1 oz), down booties (2.2 oz), cuben winter pack (14 oz: Heavyweight Ultralight Backpack ) etc.
I used this setup on a 5 day trip in 2013 here:
Glacier Divide Loop
a 5 day trip in 2014 here (BTW, many thanks for Andrew and Chris for letting me use their stove after mine failed):
High Sierra Snowshoe Trip
a 7 day trip in 2014 here:
Tablelands Snowshoe Trek
If you’re interested there are some detailed gear lists here:
Seven Day Sierra Snow Gear List 2014
Winter Sierra Gear List
It took a few years and some very cold trial and error (like using a 40 degree quilt in 15 degree weather) but this seems to be working so far. I hope this helps. Andy.