phillydog,
Here's something you could try? I think it would really help in any weather condition. Not sure if the Hennessey has a bottom entrance, in which case you would need to modify this idea.
Buy a couple of those space blankets, not the cheap gold/silver aluminized one's, but the kind that are made of rip-stop material with only one side reflective and grommets on the border. I have used one as a ground cloth for 20+ years, and it's still rip free.
Hang your hammock and determine how long it is with with you in it. Take the space blankets and lay out the long way, overlapping them enough to stitch together. You want the over-all length of space blankets to be LONGER than your hammock.
String up your hammock, and using clips/clothespins etc, fit the blanket to the hammock. When you pin up each end, you need to leave a hole for hammock straps, allowing enough room to stitch up the remaining end.
When you string hammock, you just slide hanging strap thru end hole and you have a similar rig as the hammock mosquito nets.
You can use Velcro/snaps to close the top off once your in hammock or not. A little experimentation in the back yard should work the kinks out

It will cut down on wind/evaporative heat loss, reflect body heat back and give you a place for clothes storage.
I don't think condensation will be problem, as you can open the top as you need.
You could clip/pin everything together before sewing up, and if it doesn't fit you needs or is to unwieldy, you just wind up with a couple of space blankets/ground cloths