re: Full sun heat tolerant tree

For some other (40-60ft) options, have you considered sassafras & catalpa trees? Both are fast growing natives & have good color.

Catalpas are kinda short lived but don't seem to get large enough to do damage when they fall. The bean pods look cool & they also have nice flowers.

I have a massive willow oak, it's a great shade tree, but they are almost evergreen here (SW GA) and you're even further south, so not sure about the fall color. It is bulletproof though & grows very quickly.