Q 1: why not pleat both layers (running perpendicular to one another)? It strikes me that by doing this you could a: create larger air spaces, or b: even better, create more air spaces (depending upon the up or down orientation of the pleats).
The reason I ask is that I am presently in the design phase of a TQ / UQ of my own. I want to do everything possible to maximum R value with two layers of IX (because I'm cheap) while minimizing the learning curve (because I'm a "noob"). Already I know with complete certainty that I will be "press ganging" your idea concerning the pleats (l just love it). Likewise,I have no moral aversions to high-jacking any other tid-bits of wisdom you may care to impart (that's why we're all here together, right).
**As a caveat, I should add that nothing I make is for resale (period). I'm just a cheap ******* who would rather make my own gear than pay (some other cheap *******) for it.
And on the subject of R max:
Q 2: Assuming one were to pleat both layers of IX, is it possible then to insert a reflective Mylar sheet (i.e. space blanket) in between the second (pleated) layer of IX and the outer rs nylon shell as a means of boosting the R value, or would this only exacerbate vapor retention issues?
My rationale is that on a UQ it might serve the dual purposes of wind blocker and heat reflection. I am clueless as to how it would work on a TQ in terms of a: noise when shifting position, and b: vapor retention. I am certain that many of these ideas have already been repeatedly tossed around on this forum. But, gad zooks, I only wish I had the time to comb through it all.
I hope that I have provided a spark for some new thinking, and I look forward to continuing this discussion.
Jeff (in Montreal. QC)