I cooked up another version today using my modified Grand Trunk Ultralight. The GTUL can really benefit with some windproofing. The fabric breathes very well, which is a good think on a hot summer day and that is probably the best use of an inexpensive, lightweight hammock.
So I strung it all up and tried the UnderTaco as shown in the previous photos. It worked the same as it did with my Hennessy Expedition Zip. I was using the materials as found and I have to concede that the 86" long fabric of the outer cover is just too short. It will provide coverage from heat to toe, but barely, leaving the tips uncovered and a source of heat loss. I think it is perfectly feasible to make a whipped end cover, but it should be just a bit longer than the main hammock. I have to admit that my UnderTaco gives as much or more coverage as a 3/4 UQ.
I took a run at it using just a HeatSheet and that works fine for a quick and dirty under cover. In fact, I think it is a technique than everyone should keep in mind. If you ware out and your UQ was soaked, damaged, or lost, making a UC with a space blanket and lining it with spare clothing or forest debris just might save your bacon. The technique could be used with a functional UQ to extend the range and protect for wind and rain. A HeatSheet is 96" x 60", so you can get more coverage than my first attempt. I also tried lining a whipped end space blanket with another loose space blanket and that worked well for a make-do UC too. If you crumple the inner blanket, you get quite a bit of trapped air.
One think I noticed is that gathering the ends actually wastes quite a bit of the fabric. I strung my GTUL with a ridge line and used that to help hang the UnderTaco, and whipped just the top corners, making more of an envelope. That allowed a lot more coverage on the sides and importantly, around my head and shoulders. I tied the line from the UnderTaco to the ridge line with a tautline hitch. That allowed leaving the cover slack until I got in and then I could just reach up and adjust the tension. That prevented any stress on the sides on the undercover while getting in and I could dial in the space between my backside and the outer fabric.
For a no-sew rig, that worked pretty good. It does leave a fair gap at the ends. In a pinch, you could duct tape that lower gap in a second. If I were going to sew something like this, a canoe-bow kind of shape could be worked into the profile of the cover and line or shock cord could be run down the sides in channels. A space blanket and/or foam pad could be used inside, as with the SuperShelter.
I will soon have a poncho version that I collaborated with another HF member on. It will made of silnylon, and 108" x 60". It have a slit head opening, a short collar (no hood), and shock cord/drawstring channels on all four sides. I plan to use it like the Hennessy under cover with a space blanket. I plan on experimenting with alternative insulation. I think it screams for an Insultex blanket. The poncho feature will drop my pack weight by the weight of a rain jacket and I'll get the weather shield feature, a pack cover, and a possible ground shelter out of it too.