What you do is arrive to the park early at 8am, take your lap, enjoy walkon rides, and by the time you come back to the front of the park, it's noon and hot.
That's when you go back to your room, eat lunch, take a nap, maybe the pool, come back at 4pm. Grab a drink on your way in at CityWalk, Nascar, or Buffetts. Back into the park, grab another happy drink before 5pm, go on some rides.
From 12-4pm is the worst time to be at the park. It's packed, the heat burns up the pavement and makes things very hot.
When you arrive at 4pm, it will still be hot, but not even close to the afternoon. The sun will go down, you'll have on clean cloths, you're rested, and you'll enjoy the evening.