Time: 01:00 to 06:30
Location: Super-secret (wait, what do you mean "Not a secret any more,"?!) front yard testing area.
Conditions: 50 F at start of test, dropping to 46 F overnight. Winds light and variable. Near 100% humidity.
Top Insulation: Poncho liner top quilt.
Clothing: Thin polyester balaclava (hoping to replace heavier Thinsulate hat with this on trips above 40 F), long sleeve merino base layer shirt, nylon athletic shorts, nylon/spandex compression shorts underwear, thick, loose wool socks. My normal gear for expected-40s lows.
Result: Not a total success. The IX layer of my DIY modular underquilt system is a two-layer, full-length design. I found it adequate for the temperatures described, but would have been chilled had there been significant wind or if the temperature had dropped another five degrees. I was really hoping to get 40* out of this layer, and it just isn't quite enough for that. Ah, well, it'll still get me to 45 fairly comfortably. That's enough for most of the year down here. And it'll still insulate my legs tolerably well when I do the torso heater layers of my underquilt in a week or two...