I can only get things to air dry outside if we are having one of those super hot and dry dry dry spells. Anytime the humidity is the slightest bit high I get some mold or rot forming on things.

I've only dried field corn (unknown variety) and sweet corn (every year I try a new variety) and from now on I will only dehydrate sweet corn. The flavor is just sooo much better, not only sweet but cornier.

You might check out the catalog of Southern Exposure Seed Exchange. They're based in VA but carry a lot of varieties that do well throughout the south.