I remember that on our maiden trip home to California from Backus, Minnesota in late August 2011 we had a problem with condensation. The worst part was when the bedding got wet from the condensation dripping from the back emergency vent. In addition, the fiberglass surfaces were moist. It was uncomfortable if your head was near a fiberglass surface when sleeping because it was cold and wet. I, too, noticed that this happened when all the windows and vents were shut tight.
Since that trip I crack open at least one window and one ceiling vent if there is no threat of rain when I go to bed. That usually takes care of the condensation and provides a refreshing exchange of air. In addition I have created block-out shades that not only block out artificial lights
and sunlight but also serve as insulation (see photo). The block out shade at our head is sealed all the way across with the hook side of hook and loop fabric, AKA Velcro, (and the window is shut closed) so no cold air flows down on our faces (on cold nights). The other block-out shades only have bits of hook fabric on the bottom so as to let in the air from slightly open windows.
I also have a block-out/anti-drip system for the roof vents. I simply cut a square of "flannelized rubber" (available at baby supply stores) and sewed a bit of the hook side of hook and loop fabric to the corners. This fabric is then "hooked" onto the rooftop "ratfur". Any small drips of condensation are absorbed by the flannel and it blocks out a bit of the light
For comfort in bed as well as to protect the rat fur from getting aged too fast I surround the upper walls of my bed with a baby crib bumper! ($5 from the thrift store) I simply sew a few bits of the hook fabric onto the back side on top of the bumper and attach it to the "rat fur". You can also place the bumper at the side head of the bed to eliminate touching the cold fiberglass. The bumper also serves to cover those nasty metal table catches on the wall. (See photo). Note also the net mesh pockets I added to the curtains for nighttime storage (Kleenex, eyeglasses, lightweight flashlight) and the cloth pockets that are attached to the rat fur. You also get a glimpse of my "glamping" (glamorous camping) decor. This was my Hiking in Autumn theme!
'Hope these additional ideas help.