I'm in Auckland, NZ. It gets pretty muggy here although not as hot over your way of course.
My roof is insulated to reflect heat away, my walls are not insulated, you want the Ob to cool down to local ambient. My floor is raised which encourages breezes and draughts to move the air. If you can encourage natural ventilation, low air inlets, higher outlets and still keep the bugs and creepies out it's the best answer.
Cool off for me is to open the roof as soon as the sun gets down to the horizon. Muggy is what you live with, aircon seems not to work too well with the roof open
