Nice write up and nic test.
WOW, CONGRATS ON THE success right off the bat with below 20 first hang! On my first hang, I woke uo shivering violently at only 22*F! And congrats on being able to push the GL Ultra 20 to such temps. As an UL20 owner, I am surprised to hear that. It is a great quilt, but I really don't think I could take it to 15 with just the cloths you used. Though I have taken it to ~11 using puffy clothing, but I did not make it through the nigh without being a litttle cool. But I might have been OK if I had used my Marmot hood and if I hadn't had so much breath condensation on the quilt.
On the other hand, that same quilt used inside the Pea Pod gets me through some serious cold while emaining quite toasty!
Apparently, signature that I used from 2006 no longer tolerated so now deleted.
Just remember, any test that you live through, is a successful one!
Always nice to have the backyard for cold weather testing. It's only a few steps from warmth and you don't have to make excuses to your buddies about bailing.
look at a Griz beak in the future,may prevent a spin around...
thinking out loud here, if i was in the setup pictured i'd kicked/shoveled snow up to the edge of the tarp, maybe brought the tarp lower and seal both long edged.
Impressive for a first hang, backyard or not you've earned your stripes.