One thing I have done when wanting to experiment when we don't get enough cold enough nights(I'm sure I get fewer than you do): just use way less insulation. So if it was a 30F night, I might start out with just some lightly insulated clothing over my VB clothing, and no quilt. Then maybe later on add my 40 year old and ~45ºF rated synthetic liner bag, when needed. When I set my PB at +6F a few years ago, I was- in addition to warm clothing over VBs- only using a Golight TQ rated at 20F- but many people have questioned that rating as being a bit optimistic. Some seemed to feel it was more like a 30 or 40F TQ. I was also inside the HH Super Shelter top cover. Whatever, I was toasty warm all night. If I had a TQ rated anywhere near the actual temps, I bet I would have been sweating like crazy and uncomfortably hot.
Anyway, it has been pretty fascinating experimenting and trying to get this out there approach to work in temps usually considered way to warm for VBs. Including the REAL test, trying to hike when it is not colder than the 30s or 40s. Often times even with the least possible insulation(unless I use zero insulation), I have ended up too damp or wet from sweat. But I must admit, as unpleasant as that is, my outer layer - sometimes just a COTTON shirt- has always remained bone dry. And when I stop, even though wet UNDER the VB- I don't get a chill. Which I sometimes do with much thicker synthetic insulation if I hike hard enough to sweat. And I have found that, unless really taking it easy, VB or no VB, I am probably going to sweat.
Another surprising result from an experiment: sitting in my house in my recliner, or sitting outside when it is somewhat cool, either way wearing just my VB shirt with no other insulation on top, and just jeans below. Surprisingly comfy, with no sweating. But I think it would have felt too clammy/humid if not for the thin Fuzzy Stuff lining of my VB shirt. Though I suppose a very thin layer of long John top would have accomplished the same.
Anyway, it has been fun and interesting experimenting with VBs.
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