Controlling Humidity in an RV
The air in a closed up RV will contain varying amounts of moisture, depending upon the local climate and the storage methods utilized.
If you are able to connect to shore power during the storage period, an electric dehumidifier is a very good safeguard against a high humidity condition. Otherwise one, or better yet two, Dri-Z-Aire dehumidifiers is advised. Open a roof vent or two, if you can, to allow moist air to escape. A roof vent cover will ensure that the vent does not allow rain to enter.
Put the dehumidifier in the sink or the bathtub so that if it happens to overflow, the water will drain into the holding tank.