I have been running the numbers and have updated the bag design. The top piece will be 20" wide at t, and will taper down to 10". I also completed a hood design, figured out total volume of down (~8800 in^3) and picked up elastic chock cord for the hood and toggles for the same.
All that is left is to figure out what fabrics I'm going to use and where to get them; after that I'll calculate projected weight and sew it all together.
I'll order the tarp material with the sleeping bag materials, so I'll have a couple of projects going at once. The tarp should take an hour or so. All that is required is to hem the edges, sew on the guyline attachments (including reenforcements) and figure out how the ridgeline attachments will work. I still need to get grommets, the appropriate webbing and the Kelty Triptease. That's all for now.