We've been running a dehumidifier on the boat for several seasons now.. we tried on of the small ones like those available at WM but it proved unreliable and not so effective here on the Wet Coast.
Now we use a midsized Sears model, about a 15 litre (4 gal) reservoir. It's a bit bulky but works very well, we keep it at 50% and paper is crisp at all times. We move it to the car for daysails and home for summer trips. In winter we do keep a bit of heat on because these types of deH's should not be allowed to freeze up (they are just chillers, after all) At 38 F you may find yourself on the edge of effectiveness with the smaller ones. We keep our cabin at about 10-12 C in the colder times.
Many of these deH's can be set up to drain into a sink rather than collect the water in a tank.. in that case leaving it on the galley counter may work well. We find that the reservoir fills quickly initially, but once the boat's environment stabilizes the collected moisture tapers off.
When it's not really cold the waste heat from the device is enough to keep things from getting too cold (that may not be true of the little ones)
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)