With the recent cooler weather, I recall last fall and winter when I first started living in a trailer.
We were in the midst of a severe drought, unless you were living in a trailer.
Travel trailers are designed to be sealed up for storage an travel. They are also designed to minimize the enclosed volume. This means moisture does not escape from a trailer and there is a limited ability for the trailer to absorb additional moisture. Left closed up even in moderate to cool outside temperatures moisture accumulates in a trailer much more than in a house.
Moisture is generated from cooking both by water vapor from the food and water vapor formed by the combustion of propane. Moisture is obviously introduced by washing and bathing. Just sitting around people give off moisture in their breath. I could tell the difference in the interior environment when She was there. The moisture released by two people results in an entirely different feel.
In a house this does not matter because the amount of moisture is a relatively small compared to the volume of the house. In an old house in New Orleans you can barely keep the heat in. You can often feel the wind blowing through the house. At least I could in the camel back we lived in uptown.
The only solution is to actively operate the trailer in response to the weather and use. You can run the air conditioning all the time to keep the interior dehumidified. That's pretty much what we did all summer. Last fall I opened the trailer doors, windows and hatches up to allow the moisture to escape. It worked pretty well as long as temperatures were moderate and humidity was low. It doesn't work well when temperature are low or humidity is high.