The best way to make sure your RV doesn’t get overrun by condensation is to prepare for it. That means removing those “triggers” which allow condensation in the first place.
Whether your RV is winterized and parked for the season or you are living in it full time, these are things you should do.
First, is to make sure your RV is as air tight as you can make it. Make sure windows are closed, doors are closed tight and if you have storm windows, install them. Perform an inspection of your RV inside and out and look for places where cold air may enter (such as around your water, sewer and electrical hookups).
Also look for any voids which may allow cold air to become trapped. Be sure to look inside any of your basement storage compartments in your RV as well. That is because these can be subject to condensation by having warmer air from the floor migrate down into the cooler storage spaces.
For example, in our Class A there is a void behind the 3 cabinets we have above the drivers and passengers seats. Originally the middle cabinet was where the old tube TV was installed, while the cabinet above the passenger seat contained the signal switch, antenna booster and other electronic gadgets.
The compartment above the driver’s seat is mostly empty. Both the compartments above the driver and passenger seats are fully enclosed and even have spray foam installed around them, so they are free from condensation issues, but the center cabinet is open to the plastic header where the marker lights above the windshield are located. Obviously it is built this way so you have access to, and can easily change the bulbs, but in our RV this is an area prone to condensation. We addressed this by first removing as much moisture as we could that was already there (and there was a lot) and then adding a moisture absorbing product. I then enclosed the middle compartment with reflectix to help reduce the amount of air moving from inside the cabin to the void.