Sure. DampRid, StayDri and several other products are available to reduce the moisture content in the air. We use the DampRid containers in the bathroom and place one behind the passengers seat but in humid conditions they have to be changed out fairly frequently.
If you are storing your coach for longer period and have your coach plugged in, there are some electric dehumidifiers that will really remove the moisture (anywhere from 17 to 80 pints per day) but they do take up some room. http://www.allergybuyersclub.com/com...midifiers.html lists a number of units. Sears lists one that you could put up on the kitchen counter when you were not using the coach and let it drain into the sink that removes up to 50 pints of moisture per day that is a little larger than 13x21x15 http://www.sears.com/sr/javasr/produ...seBVCookie=Yes.