I collaborated with another forumite and got a silnylon poncho made to my specs to use as a SuperShelter clone on my Hennessy Expedition. The poncho is silnylon, and 60" x 104". It has channels in all four side. I strung the sides with 3/32" shock cord and used 1/8" across the ends. The side cords have toggles and the ends have toggles and one mitten hook. the shock cords are full length, so the hems aren't drawn in when used as a poncho, although the one in back might work well draw in a bit.
The poncho hangs just below my knees in front and almost touches the ground in back without a pack on. with my pack in place and a cord around my waist, it will cover my pack and flap less in the wind. The head opening is a slit and has a collar rather than a hood. There is a drawstring at the top of the collar, so it is more of a "gasket."I wear a Tilley or Outdoor Research hat for rain gear rather than a hood. Since the head hole s on the bottom in weather shield mode, it doesn't need to be water tight and the drawstring on the collar will take care of air any major airflow. The bare poncho is just 7oz--- more like 10oz with all the toggles and shock cord.
In weather shield mode, the end shock cords are drawn fairly tight and clipped in a circle with the mitten hook catching on the toggle on the opposite side. The circled shock cord is clipped into the stock Hennessy snap hook-- the one on a Prusik hitch on the suspension that is normally used for the tarp. That gives about 90% coverage to the ends of the hammock. The side cords are drawn in about 12" on each side and give good coverage up the sides. I'm still in fiddle mode and working to get the sides and ends drawn up for the best fit with the asymmetrical layout of the Hennessy. I'm very happy with what I have so far.
For insulation, I've been experimenting with single and doubled space blankets and I'm surprised how well they work with a cover like this. I'm also trying combinations with a 5mm EVA foam pad. I'm not expecting lower than 50F with just the space blankets. I'd like to get to 40F or below.
WV warned me about condensation issues with this setup and understand his concerns. I don't see any more opportunity for condensation with the poncho than with the Hennessy under cover, but we'll see. I'm going to give a test run tonight, with 55F and 70% humidity and a 50% chance of rain.
I'd love to try a Insultex pad with this.
I give you the UnderPoncho