We got a wonderfully efficient little de-humidifier (and where I live it is a necessity!!) several years ago from an RV supply place that has since folded...
. I would like to tell you the name but we have renters in at our trailer at the beach and I do not want to disturb them to check. It stands about 2 feet tall and maybe 8" in diameter and takes up to 3 cups out the air daily if necessary.... It turns itself off when it is full. Takes about the same electricity as a lamp. No special care at all is required. I had never before seen one that size and most that are sold around here, even now, are huge and for whole houses!! Anyway, wish I could tell you the brand name but did want to tell you they exist. I bet Camping World or some of the larger US places would have something comparable... Good luck!
jan
PS Should warn you that it was not cheap...I think 75 or 80 bucks as I recall but everything here is expensive LOL! Then again, my super little 1500 watt space heater (that is an amazing propane saver!!) cost only 35 a few weeks back!!