[jimcol]

We experienced the exact same issue first time out in our first hard side RV. (Never an issue in the tent or the pop up). The camp host noticed our windows all fogged up. He explained that just the two of us in there breathing expels moisture into the air, coupled with the propane furnace. Even though we were trying to heat the place, keeping one of the ceiling vents slightly open will eliminate moisture build up. Didn't make sense to us but we tried it. Worked.