Alright, 40F is the lowest temperature that this will be in. Let's say at the coldest point of the night, it will be 40 F. The highs for days like that (depending on overcast and elevation) is high 50s to low 70s in TN. After hiking, I arrive at camp and setup my things. As it gets cooler, depending on how cool it gets, I will wear all of what I have. I will add the bottoms under my pants, and I will add my silk over my base then wear my WindShirt. I cook, read, write, talk to hiking partners, then go to sleep. Maybe it is that I am warm blooded but I don't forsee a problem here. This season I anticipate being on the AT as well as the Cumberland Trail, all typically below treeline. If there is an incoming monsoon trip will be postponed.
In terms of backup insulation, I do understand the inherent risk and need for testing these garments, but that inherent danger exists when you use a 20 F quilt in near 20F temps. This clothing list is hiking, sitting at camp, and then sleeping in nothing below 40 F.