Coastal hay is fed a lot in FL also.
Being you leave out loose salt you could try leaving out loose minerals and vitamins as well in a separate bucket/pan. It'll be hard to find one that's not trace mineral though, if you go for a block.
I like Valley Vet for their prices and variety in products and sizes offered. Some of the ones I've heard good things about are:
Clovite, made by Pfizer
Mega-Cell (for grass/ grass hay diets.) made by Med-vet Pharmaceuticals
Barn bag, made by Life Data Labs
Maxum Crumbles, made by Horse Health
horse-Manna, made by Manna Pro
Free balance 12:12 crumbles, made by Purina.
There are other choices out there but those are a few I've heard good things about. You could also ask a vet or feed store associate about good vitamin and mineral supplements.