I've been here long enough to really acclimate, and I still try to get my biking finished up by 11am during the summer. It really isn't the heat, it's the humidity. I did a race last year where one of my bike rackmates was saying he was just back from Saudi Arabia, and he felt worse here than he did there with 120F heat and 5% humidity. But the other 10 1/2 months here more than make up for any late summer discomfort, IMO.
What I'd suggest is an early morning breakfast ride. Get up with the sun, get riding, and pedal over to one of the cafes open for breakfast -Hibiscus Coffee in Grayton, WaterColor Market, Modica Market in Seaside, Summer Kitchen in Rosemary Beach, etc.- and enjoy a really nice meal. Then grab an extra drink to go, and enjoy exploring some more before it gets too warm. It's what all the local roadies tend to do when the weather gets cranking.