Kathy, (Grass Valley, CA)
The first thing to do is get those vent covers installed even if you must take your Safari to an RV service facility. During use, keep the rear-most roof vent opened and the forward-most window cracked open slightly. The process of convection will move a lot of the moist air out. This air movement can be aided with the addition of a small electric fan or with the air conditioner fan when connected to shore power. A small, portable dehumidifier or two may help as well, but again they should be used only when 120-volt AC power is available. The use of a silica gel desiccant will also help absorb excess moisture in the air.
Finally, on those chilly, rainy nights set the furnace to a lower temperature setting. Combined, these methods will help reduce your moisture problem and further prevent the formation of mold.