Last Nov/Dec I was working in Chatsworth from dawn until 10pm, outside. Always took a break around 5pm to go put on the long underwear so my body could start heating itself for the low 40 temps that were soon to be upon us.
For staying cool, I use the portable AC units to get a nice breeze every now and then. Have a hat with a large brim all the way around. And a nice cooling bead neckerchief (it absorbs an insane amount of water) to keep the neck/arteries cool.
Of course my methods can't always apply to a cast member who is in costume.
I try to avoid going to Disney World in summer because of everything you said. Having said that, last year I went there in October, and the temperature climbed to the 90s (like summer)and it was just awful.
We Floridians have two options:
1) Drink a lot of water
2) Go to Disneyland where the weather is great in the summer!!
Let the tourists have the parks from June until October! Now don't get me wrong, we still go to the parks almost on a weekly basis, but we go there to ride a ride or two and eat lunch and then leave! We do a lot of indoor things in the summer. Heck, we don't even go to the water parks until fall!
If you are going to brave our summer weather you need to be prepared and in shape! If you are overweight and have no cardio endurance to speak of, then you should only plan 4-6 hour days of theme park activity here and take advantage of your resort or hotel's pool. We see people every year come down in July and try to pack 10 days into 5 and leave with the most miserable memories one could have on a vacation!
As others have stated, go to the parks at rope drop and enjoy the coolest part of the day (which in the summer is still darn hot and humid!) and it is quite often the slowest part of the day because many people eat breakfast at the resorts and get a late start.
I would also make priority seating arrangements before your trip and make meals a part of your vacation! The eateries at all the parks in Orlando are wonderful and I remember lunchtime being a fond vacation memory for us each year.
Go ahead and come down in the summer and take it all in....just not all in one day!
I also agree with not going in out of the cool ac.
Plus water water water water and sunscreen every few hrs.
When I worked in Tomorrowland, CMs had to wear long pants at all times. Only at Speedway did they have the luxury of shorts, though they had the blistering heat and fumes to deal with. There was little shade if one was at a greeter position, and if you got stuck at Astro at the wrong time of day... forget it. That was one place that the cooler was allowed relatively onstage.
Contrast that with DAK. I was allowed shorts, the greenery allowed for shade, and if you were in the sun where I worked (Everest) it was because you weren't smart enough to find shade. Also we had these great things called fans there, something that didn't hit Tomorrowland until I left there.
So I never got really burned in Orlando. (Even though my skin is really pale too) But it always amazed me those people that where red, (tomato-like) even with blisters and kept at it. I know what happen to them, more than likely they thought the Orlando sun was as tame as the one they had were they lived. Boy are they wrong!!
I wonder if the locals have a name for these folks?
I always go with a cap, glasses, sun proof lip balm, I put on sun screen before and another time during my stay there so I haven't really gotten burned badly.
But I do remember my first time at IOA, the year they opened, I got a case of Insolation. I couldn't sleep, my mind kept going and I felt like I was on a roller coaster in bed all night! It was bad!
But the next day I felt better and we went on with our trip, we still had like 4 days to go. It was like our 5th day on a twelve day trip with parks on nine of those days. Yes, we were troopers!