The first set of gear our troop made 6+ years ago was with 2.5 oz. Climashield XP. I got a really generous donor to help out our project and it saved us a bunch of money. Two layers is supposed to get you to around 20* so that's what we did. We made TQ at the time, about 16 in all so we used some remnents along with the 4.0 oz Apex this time. Apex is reported to be easier to compress than XP, but we have not had in the field enough to confirm. It was a heckuva a project and the boys learned a lot about making and taking care of their own gear. When they are invested with time, money or both they sure treat their gear differently.
We used 1.1 oz untreated for the inside of the UQ and 1.3 treated for the outer shell. I had them trace 2" wider and longer all the way around my UQ then cut the Climashield to fit inside, wrapped the edge of the 1.1 oz over the edge of the Climashield and stitched an edge. We followed with a similar flop and wrap technique with the treated material, using a rolled (fold over as you go) seam that also served as a channel for the shock cord. Tensioners for the ends were stitched in on one side and cord locked on the opposite and one cord lock for the suspension, which needed to be tugged tight to snug to the hammock.
They work really well and the boys only have a few more nights to earn their merit badge. I am working on some neckerchief slides from potato vine clippings with a hammock between a couple "trees" as a special award for the first group.
Good luck on your projects.