In a hammock in the cold I always use a reflective foam winshield garde
right under me in the hammock. I have never had condesation using that method. Its a insulating layer , VB and gives shape to the hammock.
When the VB is between the insulation and the outside air you will have condesation in your insulation and may cause it to fail.
I have found in the deep cold if a use a highly breathable bivey bag or hammock sock I will have some condesation on the inside of the hammock sock.
Thats ok, I know the condesation is not in the outside layer of my
insulation area that will cause it to fail. Hanging in a large tarp will can cause that.
The air around your sleep system is so much colder it will cause some of your
water vapour from your body to freeze in the outside layers of your sleep system before it escapes to the outside air.
Wearing VB systems work, but I find them to be to much fiddle facter and
to uncomfertable to my liking and would rather use other meathods to manage
In the deep cold in 2-3 days you will have to dry your gear by sublimtion
or a form of heat. Or it will be at best less effective or fail.
I think temps between 30*F-40*F and damp are the worse for trying to stay dry and warm then -0*F and takes a
whole different approch to ones methods and are two different disciplines.