As usual, I attempted to save $$'s by making a synthetic UQ. Then I made an IX UQ. I have adjusted both every way I can and still end up with CBS in 30 minutes at only 60*. I simply can't get them snugged up and sealed off properly.
I finally gave up and got a HG 20* Incubator with 2oz overstuff and a matching Burrow to go with it.
I tried them out yesterday at 40*F with a 5 mph breeze.
First I tried the incubator on a long, wide gathered end diy hammock. I had to cinch up the ends slightly and that was it. Instant warmth and no CBS.
Then I tried it on my new WBBB and made no additional adjustments. Instant warmth and no CBS. Did I mention I dozed off...testing is such tiring work.
The Incubator simply fits. The shaping is superb, allowing it to mold to the hammock and leave no gaps.
Oh yeah...the Burrow ain't bad ether.
Thank you so much Adam and Jenny!!!