This weekend at my hang I had some pretty cool temps, and it made me really wish i had a good TQ....
But I did have a 55* mummy bag (not meant for fat people) and a Poncho liner blanket....so I improvised.....
Heres the basic idea, if you have a Poncho Liner and an exposed RL (or even a way to tie it like a tarp)
Throw it over your RL length wise, giving you about 3.5 feet draping down the sides. I tied the center strings around the RL at first, but then switched it to tying it UNDER the RL and had better success overall with that way, since the top of the PL will droop slightly...
In the under RL setup, i tied the strings of the PL on the foot end to the area past the gathered end, basically sealing it off and the head end could slide along my RL.
Then, tie the CORNER strings to themselves, basically making it a tube, but LEAVING the center strings (on the long edge under the hammock) untied so you can get in and out still.
if you wanted to improve this design, you could add a strip of fabric under the hammock (basically connecting the 2 long edges) and it would double as a UQ protector, but my idea is to take 2-3 lengths of shock cord and put them across to pull the bottom sides snug and sealed.
What all this does for you is make the hammock its own greenhouse, with a vent of maybe 6" at the head end (far enough away to not get a draft). condensation was NO issue at all, and i never got a draft. I was able to get loosely in the mummy bag and put my button down shirt on backwards (all i was wearing was shorts & a t-shirt) to cover my arms and i was more than warm enough in weather that was supposed to be in the 40's. YMMV
so if youre not a UL guy, try this out. works really well except for high winds (it did get pushed in a little, but not so much to loose the greenhouse effect)