Hi, I also live in Florida and have several ducks. The summers here are not as hard on them as you might think, as long as they have water, all the time. The kiddy pool is a perfect idea, but be prepared to change the water daily. When a duck starts swimming, they will poop.

Now in our case the ducks run free, more or less, in a big fenced in field, with a water hole just for them. But we have one duck that was born with a leg problem, so she is fenced in a smaller area, but even at that it's still a large area. She has her drinking waterer and a small barrel cut in half to fully get wet and do the duck thing. Half of it is shape, the rest full sunshine. The need both and they also need room to feel free. No small cage, in less you are planing on taking her/him out daily and letting her/him have plenty of play time.

As for the fan, is you build the shelter right, you should not need it. This is what we did. She has a roof for protection from weather but then the rest of the shade is plants and this dark screen like stuff, that keeps the sun off her but still lets air get in. I was really surprised at how cool it really was under there, the first time we put it up. She seem happy with it and we have had her for years with no problems durning any summer heat.

Hope some of this helps you.