Find a way out, move to Colorado. ;-)
I grew up south of Mobile, AL ... summers were brutal.
Went to Colorado Springs to the OTC in mid summer; it wasn't oppressively humid, then set out to find a way to get out of the south in the summer. Found a job in Yellowstone, worked there for 2 summers.
That aside, we often did runs that went by golf courses which had both water sprinklers and water fountains. I worked at night till 9:00, then members of my XC team who were in town would meet at 10:00PM to put in our miles.
Stay cool during the day, and cool off after your run ... at some point, I think that training in the heat and humidity is detrimental for say an entire summer, and really don't buy into the idea of just toughing it out. Drink plenty of fluids during the day, and during your run, etc. If you can get into a pool after a run, go for it ... or if you can take a dip in the pool during ... go for that as well.
I tended to avoid eating a lot of meat during the summer and think that I may have lived on spaghetti, watermelon and other fruit.
From my experience with the southeast during the summer, I don't think that there is any problem with doing your quality runs on a treadmill in front of a fan or a.c.
I would suggest that you double up on a multivitamin, and think that you lose a lot by sweating so much ...
Wear a hat, and put some ice cubes under the hat ... stash some cold water along your routes, or carry cash to buy something to drink at 7-11, etc.