Some condensation is inevitable, we made a reflectix artic pack which helps a lot but adequate ventilation is critical. Except in the coldest weather (20's and below) we almost never close the window at the very front of the camper with the two of us and a large dog on board. We heat with a Wave 3 and leave it on low at night, sometimes have to turn it off because it gets too warm. In the morning we flip up the mattress (we don't use the stock cushions) and open all the windows. If it's sunny and or there's a light breeze, any condensation is gone pretty quickly. The other thing we do is leave the front window open and crack open one or two of the tiedown access doors while driving. This is mostly to provide ventilation for the dog but it also aids in removing any built up moisture.