RE: Anyone know about bivy sacks?
Dirt2: I did the bivy sack for a while. It did keep the rain off and seemed to increase the insulating quality of my down bag. This is true as long as the sack is loose enough not to compress the down bag in the slightest. But yes I did have the condensation problem. And in a down bag, that's bad. I would use it if I had no other shelter.
But I would suggest a high quality light-weight one man tent. I believe Marmmot, Kelty and North Face all make one. The North Face Solo 12 weighs only 2 LBS, 2oz. Kelty's lightest, the Stick 1 weighs 2 LBS 8 OZ.
But lately, I just bring a 4x8 tarp and some twine. I find a couple of poles on sigt or use a handy tree to rig it. It doesn't keep bugs out but in the fall evenings, the cool air seems to keep the bugs inactive. As long as there is some air between my bag and the tarp, condensation is nill. And I have kept dry in a pretty big rainstorm. But you must pick your spot with care. Pick the top of a small knoll and dig a trench around the tarp if you can. Avoid grassy area as they indicate a place where much water collects.
okcmco