I worry about burning pads on hot asphalt. You can toughen (thicken) pads for some added protection and/or you can use booties. Either way it is important to keep an eye on your dog and notice when he is having trouble with hot surfaces.
All of my dogs are mostly black. I need to be careful even on a cool day. Last year, on a comfortably cool day (low 70's), my solid black bitch, Luna, overexerted herself (playing frisbee) right into a seizure. Any dog/person can have a seizure if their bodies are pushed hard enough. Anyway, Luna doesn't have the good sense to stop and rest when she gets hot, and because I felt comfortable I didn't notice how hot she was getting. By the time I got her to the vet her temperature was 103 and dropping.
In an emergency you can cool a dog quickly with rubbing alcohol, especially applied to the pads. This is hard on the skin, so it should be reserved for an emergency. That's what the vet had me doing with Luna.
Cole carries a folding water bowl in his cape so I can give him water from fountains or bathroom sinks. I carry water for each of us when we'll be away from plumbing.
Melissa, of Melissa and Dharma/Tao, used to make cool capes. I've seen a few other versions as well. They're capes made of a cotton mesh that can be wetted to cool a dog. Those cordura nylon vests can get quite hot. I make summer capes for Cole out of cotton prints for that "designer" look.
A very fine mist can be cooling as well.
I saw a crate fan in the Pet Edge catalog that has a removable core you can freeze to cool the air being blown at your dog. It's battery operated, so you can easily take it with you. I don't handle the heat well because of some of my medication so Cole doesn't wind up in the heat either. If he did, I'd seriously consider this ice core fan.
I've tried the cooling neck wraps myself. I'm speaking of the kind filled with crystals that hold a lot of water. Personally, I didn't find them helpful, but your mileage, and your dog's, may vary.