After being used for a season, a camper/caravan can get really moist inside. The mattresses, pillows and similar items can literally contain many liters of moist. It is recommended to remove such items from the camper/caravan before parking it for the off-season. Before locking it up it is also strongly recommended to give the camper/caravan time to air, so the largest part of moist can escape. After removing the mentioned items and proper ventilation, you can place or more Pingi bags inside (The same goes for boats).