H2O is definitely a by-product of combustion, but the amount of condensation is also
dependent on the relative humidity of the area where you are camping, the temperature,
the number of breathing bodies, etc.
I usually find there is less when I am camping in the dryer southwest and more over
around the coast. At my chronologically advanced annular condition, I don't breathe
very much and have to take my pulse in the morning to see if there is any point in
getting up.
Jerry