Shug and I headed up to the Superior Trail for a coupla nights of snowshoeing. My gear was my typical HH stock configuration with added insulation. Hammock picture here: That's me with my head behind the tree...
Yes, my tarp isn't real taut, but we weren't expecting any snow so I didn't bother to tighten it up.
Gear common to both nights:
Hammock: HH Explorer UL, stock tarp, Supershelter + overcover
Bag: 0F REI Zenith mummy bag, synthetic insulation
Clothing, torso: smartwool SS T-shirt, LS Powerdry shirt, Marmot Precip jacket for VB
Clothing, legs: Powerdry longjohns, Marmot Precip pants as VB, polypro ski pants, 200 wt Polarfleece pants
Feet: silk liner socks, bread bag for VB, heavy wool socks, 400g Thinsulate boot liners. 1L insulated Nalgene filled w/ boiling water pressed against bottom of feet.
Head: Psolarx fleece balaclava without the heat exchanger
Night one, -5F: in my Undercover, in addition to standard space blanket, did my typical cold-weather configuration of Exped Multimat on the bottom, and a down jacket under my back in between the OCF and Multimat.
Clothing - Torso: 200 wt Polarfleece pullover as outer layer
Night two, -27F: added my down +30F REI Sahara down bag between Multimat and OCF in the UC.
Bag: added fleece bag liner, and Primaloft parka thrown over legs
Clothing - Torso: 300 wt Polarfleece as outer layer
Clothing - Neck: fleece neck gaiter to pull up over eyes
Picture of me in the 300 wt Polarfleece here:
This is an LL Bean Ascent jacket that I highly recommend for VERY cold weather. It is much too warm to hike in when the temps are > 0F, but I was comfortable hiking at -20F and it worked well at night.
I was plenty warm both nights. No sensation of cold except for the bridge of my exposed nose.
The hassle factor on night two was excessive. I do OK getting into a mummy bag in my HH, but the fleece liner was a struggle with the fleece clothing I was wearing as an outer layer and little wiggle room with all the layers on. Too much friction, no sliding, no space.
The overcover worked well - really kept the cold wind off of me. Lots of condensation on night two - about 1/4" on my reading glasses hanging from the RL.
The down bag as an underquilt worked very well. The SS OCF pad is "sticky", and I use the Exped Multimat with the "sticky" side up so anything I put between them stays in place all night long without moving with no cords, tiedowns, etc.
The synthetic mummy bag contributes a lot to the warmth. It doesn't compress nearly as much as a down bag so I needed a big pack (90L) to carry it in, but didn't compress as much beneath me either.
I used a lot of fleece in my configuration, and that holds up well under compression as well.
This was my first attempt using VB liners. The Precip jacket and pants helped out a lot, but getting the pants off & on to pee was a pain in the butt due to the Velcro attachments and zippers on the side. The bread bags worked great as VB socks, but I used them only at night, I didn't hike with them.
Summary: it is possible to use a stock Hennessy configuration with Supershelter in arctic-type conditions with the addition of a LOT of additional insulation. I was able to re-purpose gear I already had without going out and spending a bundle on down UQ's.
What would I do differently? If I had unlimited $ I'd go out and buy a -40F bag. The biggest irritation was all the !@#$%^&* layers I had to wear. On night two I had to pee 3 times (it was a good thing I had a Gatorade bottle in the hammock so I didn't have to venture out), and getting all my pants pulled back up properly was a pain. The first time I got all done and noticed my underpants were still down around my knees Plus with a -40F bag I wouldn't have to change my clothes so much from what I was hiking in. Nothing like getting down to your skivvies at -27F in the morning to get your blood pumping
What I'd like to hear from other folks is: "What's in your Undercover?". I've tried all sorts of things, from Garlingtion insulators to parkas, and you can see where I've ended up. I'd like to hear what others have tried and not abandoned.
Hope you find this useful.