Seems like I saw where someone here was building a WP quilt out of cuben.
I have used a vaper barrier a few time in above freezing temps and I found them somewhat uncomfortable and clammy.
That said it seems to me that with a quilt that either was mostly open to the foot, or had a foot box vent, being so open whould help the clammy issue.
Also wondering what it would be like at say 60-70 degrees.
I was thinking about poly fill, but considering its WP it might as well be down filled.
I am thinking about either a screw top vent or a small mesh area to let air in and out.
I think I will build a test run out of cheap materials first.
Any feedback appreciated.