I don't know too much about this. My dogs are indoor dogs, but I know about heat! I live in central Texas and grew up in south Texas. Here's what I do:
1. Sadie and Riley stay indoors most of the time.
2. I am careful about changing temperatures all of a sudden-ie taking them from the air conditioning out into the heat. I try to acclimate them to the heat by letting them meander around in the shade for a while or sit on the porch when we first go outside.
3. I try not to take them out in the heat of the day. I did this even when I only had Sadie... Our summers last from April through October at least, and 100 degree weather just isn't good for any dog.
It sounds like you've got the shade and water thing covered for them when they are outside. As far as her coat, I know a saint at one of the dog parks we go to that is shaved in the summers. I've never seen her with short hair, but I can tell you her hair looks just fine long. So I guess it grows back normally. Maybe it's a little kinkier-like curlier... I know my hair did that when I cut it off really short... LOL
I was told that their coats help keep them cool and that they protect them from sun damage to their skin. I guess those would be the things to be concerned most about, not the return of her hair. I'd just keep a watch on her and make sure she stays cool and doesn't get sunburnt.
