Ed,

Anything you can do to prevent direct sunlight from hitting the sides of the container will be helpful, even a sheet of plywood leaned up against the container will help. I've learned to leave containers facing the same direction so that the roots on the cool side stay healthy. The material the container is made of greatly affects heat. Wood is excellent for preventing heat gain, as are the lightweight faux terra cotta containers. Real terra cotta (unglazed) stays cool as long as it is moist due to evaporation through the sides--but it can dry out quickly and fry the plants. Dark colored plastic and glazed clay pots are the worst at getting hot.

The absorbent cloth idea just might work, although I've never even heard it discussed. I don't think it is necessary that the cloth be light colored. Dark color would absorb more heat, making the water evaporate more quickly, which in turn would increase cooling. Evaporative cooling will be less effective in the more humid areas of the state. Be sure to let us know if you try this and it works.

As for aeration, this is almost totally dependent on your soil mix. Nothing else matters.

Jason