As previously stated a closed system like an RV furnace does not add moisture to the air.
And I fully agree with RV walls and glass being cold...they will collect moisture and may even freeze a nice jack frost affect for you!
Also agree...try to reduce interior humidity if your percentages go above about 35%. We found in extreme cold we had to add moisture to keep humans comfortable because after monitoring with a humidistat our interior moisture level would drop below 15%. We were showering in the house so we had to actually run a humidifier 24/7. If you find your humidity is way too high buy a dehumidifier.
No matter what you do...even with the humidity below 10% at certain outdoor temps you will get condensation...it's just a fact of life! We just found it was just too durn uncomfortable to let the humidity drop below 20%.
