If you don't camp in MI in July, August, I'm not sure why you would attempt Disney, except that it is Disney which makes the most miserable circumstances seem better. August in Florida is high temps, high humidity. The air is dank, so that when you get wet (like on some rides), you really don't dry off completely. You just stay hot and sticky all the time, except in long periods of air conditioning. I think camping without AC would be uncomfortable. There are strategies to make getting through the parks during the day easier, as others have said, but I can't imagine not going back to an air-conditioned space to regroup at midday or at the end of the day. I would really be dragging and not get the most out of my vacation, but you could be made of stronger stuff. Good luck!