checking back in. I recently completed a down underquilt DIY, trying to clone a JRB.
Rigging it took some experimentation. First, I used bungy cords but left the draw channels in the head and foot too loose. Luckily, it was in the 50's so I was just chilly.
The next day I tried to rig triangle thingies, but didn't like how they worked with my 78 in. long UQ.
I ended up cinching the ends down to around 12 in. Before I got a good seal.
The final suspension version uses small diameter shock cord (1/16 est thickness)., two carabineers and cable locks.
One last thing I might try is a third line on each end, from the middle of the draw channels.Old time hammocker, HOI, has this set up and it looks real snug. He doesn't use shock cord, just some real small string. I did add a shock cord from the middle of the quilt running over the ridge line to snug things up even more.(thanks shug!!!) That's when I felt the heat kick in.
I'm so glad I tried to imitate JRB's design. The difference in inner and outer panel size allows snugging up tight without compressing the down. I'm sure theirs is even better.
the worry about sleeping diagonal was a no problem. the quilt follows the form of the hammock with you in it.