While my trailer was in storage last winter, I used a couple of the "Damp-Rid" buckets. They did a good job of keeping the interior humidity down, and kept the windows from fogging up. This winter, I'm living in the trailer, so things are a lot different. There are four things that produce humidity inside an RV: Breathing, Cooking, Showering, and Heating w/propane. We don't have much control over the first, but the other three are pretty manageable. Using the range hood fan (and cracking the window over the sink) will send the cooking humidity outside. Opening the bathroom vent and turning on the fan
clear the humidity out of the bathroom (and the entire trailer) in very little time. Finally, heating with propane produces a lot
of humidity. Electric heat, on the other hand, is a very dry heat. I use my propane furnace overnight (to keep the pipes from freezing), but during the day, I kick on the electric heater/fireplace and crack open one of the ceiling vents. Seems to clear up the overnight window fog pretty quickly. A side benefit is my metered electricity is cheaper than propane (in some campgrounds, it's included in you campsite fee) so I save a little $$ on heating costs.
One thing I've discovered about winter living in a TT: the higher humidity level means I don't need a humidifier to keep my skin from drying out. I've saved a small fortune by not having to buy as much lotion!