Ventilation is the right way to dehumidify your rv.
Probably very true in a dryer climate, but trying to keep moisture at bay is a problem in the Pacific NorthWET. It's pretty difficult to keep vents/windows open when it's raining almost constantly November-March unless the trailer is either under cover or covered. I live in the east country area of Portland and the rain comes down sideways because of the wind.
"The rainfall averages 42.7 inches (1,080 mm) per year in downtown Portland. Portland averages 155 days with measurable precipitation a year. "
I think there's a mistake... 155 days? Some years it seems like 255 days <_<