Central Florida is the humidity capital of the world. I assume that yours is an older home. Most of the older homes in Florida were built reasonably tight. Older homes were designed to "breath" I would not add anything that could cause moisture to be retained inside the walls as you could be looking a mold problems down the line.
If your looking for the best method to add insulation see the VIDEO: Blowing Insulation Into the Sidewall of a Mobile Home
. This footage demonstrates how insulation is blown into the sidewall of a manufactured home as an energy conservation measure done by the U.S. Department of Energy's Weatherization Assistance Program.