Just finished my synthetic "multi-quilt".
2 layers of Climashield XP .6", (should be good down to around 20F). 42" x 72" rectangle, sewn with grosgrain loops on the corners to hang as an underquilt, and channels with 550 paracord to either cinch up as a top quilt or cinch up the ends for the underquilt. I was trying to make the size 'just' fit, with very little extra. I don't roll around much when I'm sleeping in the hammock. There are more pictures here.
And it's reversible, so if I need more stealth , I can "fade to black".