Mattress mold

I want to lay my hybrid mattress on a new solid platform frame. Because of our high humidity I am concerned about mold. A number of sites on the internet point to  this as a potential problem, and that's in the US. The suggested best fix is to put a coconut coir pad under the mattress for circulation. Has anyone one had a mold problem with a solid platform bed? I would prefer not to use the coir pad. One suggested method was to drill numerous holes in the platform but many negate that as not effective, Because of the heaviness of this mattress slats are not good as we had them before and there was sag. I would appreciate helpful feedback.