I've been sewing like crazy since completing my bridge based on Grizz's videos. I've completed my whole hammock setup over the past month and now that I've tested it I don't think I'll ever sleep in a tent again.
I went this weekend for a overnight solo trip to the Cross Timbers Trail at Lake Texoma, and the overnight low (per accuweather.com) was 50 degrees. I slept in only my boxers and was way to warm with my underquilt and topquilt at the start of the night, so I shed the topquilt but needed it later on. I was still a little warm so I figure that sleeping with layers I can hopefully get to the upper 30's with my setup.
I made my topquilt and underquilt using Primaloft Sport, 1 layer of 3 oz and 1 layer of 4oz. When finished the underquilt didn't come up the sides of my hammock as much as I'd hoped, but it contacts the sides past where my body touches the hammock. I used a 3 inch diff. cut and that seems to be sufficient for maintaining the loft and put channels on all sides of the quilt with 1/8" shock cord running through. It seals up nicely against the hammock. After struggling with the quilting loops for my top quilt, I thought it may be easier to hang the underquilt to put the loops in and I was right. What took me a couple hours to do on my topquilt took about 20 minutes for the underquilt. Hanging the quilt kept all the layers in line and made passing the needle straight through much easier. I used embroidery floss for the loops.
I also made a rectangularish tarp that is 12'x10', it's huge but covers the bridge nicely. I'll probably add some pull-out tabs where the head end spreader bar is so I can pitch the sides steeper if need be. I went with shock cord loops attached to the tarp on one end, and a prussick loop on the other end connected to my guy lines, which made setup nice and easy. The shape gives me partial doors which I think should fit my needs as I don't intend to be doing much in the extreme cold.
All in all everything works well thanks to a lot of time reading what others here have done, thanks all for the great wealth of info!!