Brian... When I was a photographer in Vietnam and in Subic Bay, Philippines; we used to keep our gear in a standard gym type locker that was modified with wire mesh shelves. We always had a low wattage electric bulb burning at the bottom of the locker.
The bulb kept the locker fairly dry while the mesh shelves allowed ventilation throughout the locker.
This seemed to keep our gear fairly free of fungus/mold. I am sure that you could rig a storage area out of Philippine plywood at a slight cost to keep your photo gear in a drier environment. Just about any type of enclosure would work - depending on the amunt of gear you needed to keep fungi free. I suspect that today, one could find a heating element combined with some sort of a fan that would do even a better job.
This might work...
https://www.amazon.com/exec/obidos/A...humidifiers-20
Another thing we did was to ditch all leather accessories which seemed to be a breeding place for mold. In those days (the 1960's) cameras traditionally were supplied with leather cases and leather neck straps. Toda, I worry when I see the leather retro cases and straps for modern DSLR and mirrorless cameras.
Of course, here in Southern California, mold is not a great problem. Most often we are well under 60% humidity and last weekend the humidity hovered below the 10% mark