"Looking for clever solutions to keeping humidity out of the boat whiles it's not use. The wife wants to leave a humidifier on and running "
Heheh. One might suggest keeping the wife off the boat and away from any power tools if that's the case, a humidifier would just make the boat wetter. (VBG)
The buckets of "Damp Rid" and other chemicals will work but you'll have to keep swapping them out as they go liquid. Other than that...I doubt "natural" ventilation would be enough, even with dorade vents or solar vents but that's all you can try, unless you go to a powered system with a dehumidifier in a sealed up (no ventilation) boat. A small dehumidifier, enough solar panels to power it averaging out with your battery bank...if the math works there's that to try as well. It might take a few days to catch up and dry out the interior before it ran at a lower rate, but there are no magic options.