Chickens absolutely do love to wade and wet their feet when it's hot. However, most chickens are not fond of having to jump down into any water so it may take them a while to learn to use a kiddie pool. If they ever do, mine refused for the longest time. Now I just make a big puddle in a low, shaded spot and they wade to their hearts content.
Coop to Protect Chickens from Southern Heat. - Page 3
When you have high humidity, the only thing you can do is open everything up. There is nothing that mould likes better than enclosed space, heat, and moisture. We get the high temperatures, but it's dry heat, so we only have to address the temperature. It's a "whole different ball-game" in a tropical climate. (I'd never realised that Texas got the humidity, I'd always thought it would be "dry hot".)
aaah, gotcha. Louisiana is very "steamy" isn't it?
You could go "Louisiana architecture" for your coop. Completely open, with some shutters for when the rain barrels down. Verandah.... (for the ladies to sit on while fanning themselves) Just make sure there are plenty of vents up top so that any hot air escapes.
(yes, I watch too many movies)