Last year I bought a 70 pint automatic dehumidifier at Costco. It has a hose and pump to drain into the sink. I keep it set for 50%, and it does a great job keeping my 5th wheel dry inside. I leave it on all the time. It has a pretty small footprint. I run the hose to the kitchen sink when the camper is at home. When camping, I push the hose through the slide seal and let it drain outside.
2013 Silverado 2500HD LTZ CC 6.6L Duramax Diesel
2014 Sunset Trail SF270BH
Holly & Buster, mini Dachshunds
2016: 1 trip, 3 nights in 1 state, 316 miles
2015: 5 trips, 18 nights in 3 states, 2707 miles
2014: 5 trips, 14 nights in 3 states, 2426 miles