Kent -
I love the title! I just arrived in Savannah, Georgia today for the national pond and waterfall convention and it is HOT

and HUMID.
Your question came up while I was talking to a few southern pond contractors.
They basically said if you pond is at least 2 feet deep and you have a good splashing waterfall (for oxygen) you should be fine.
Creating extra shade is a big plus. Use floating plants if you can - but in a pinch the foam you talked about will work great.
If you would like to be safe, you could go and get an extra air bubbler at a local pet shop. Be sure to get one with a check valve though, you don't want the water coming back up the tube if it gets shut off.
I also talked to my good friend Eric Triplett from Exotic Aquatics and he said they had a pond hit 100 degrees in the desert and the fish still made it.
Remember Koi are a relative of Carp - they are one hard species to kill!
Hope you and your pond stay cool
