I have used the small one in my Bigfoot
for the last two years during winter storage. It works well enough that I have to empty it every 3-4 weeks. The drain idea is a good one, but I don't mind popping into the trailer now and then--it makes me look forward to the next trip. And, I like to see how well it is working. I have a humidity/temperature meter and it hovers around 60% humidity at 40-45 degrees. At those temperature the unit can't seem to drop the humidity lower that high 50's at best. I would image that a traditional household unit would do better, but I think this is good enough and it is quite a bit cheaper. It does have a fan.
I have used the chemicals before but I prefer the dehumidifier because I don't have to purchase replacement chemicals and I don't have to worry about sloshing the corrosive water around when I empty it. I think that the unit removes water faster than the chemicals, but I haven't tested them side-by-side. The chemical are cheaper and don't require electricity. I did have a problem recently, however. Even though I have a small heater in the trailer that turns on at 35 degrees and turns off at 45 degrees, the dehumidifier iced up. The entire aluminum block with fins was caked with ice all of the way out through the plastic grill. I brought it inside to thaw out and it has been fine since then. It didn't happen last winter.