Stop the wind!

There were two small quarterlight windows left unfinished in the rear wall which have now been glazed to furthur cut down wind penetration into the marquee. The doors need to be sealed and some other gaps need plugging.
However, as long as the outer skin is loose there will always be violent air movement inside when the outside air is moving.
Also, unless the skin is bubble insulated, the inside will always cool down to outside temperature once the sun has dropped - the heat simply rises through the ceiling. I have been taking readings throughout the day since prior to blocking the last vacant windows and they show that the inside air temp drops to match the outside temp by the time the sun has set.
My hope is that the polyskin will at least ward of severe frost, but my worry is that when the temp drops below zero, the extra moisture inside the marquee will cause an even worse frost!