I live in a very similar environment in Southern CA. There are several successful pond owners in my area. I've seen shallow and deep ponds work successfully in the summer heat. What happens out here is that you get a high evaporation rate on the surface which creates a lot of cooling. I think that with a waterfall and some method of top to bottom circulation, water temp should be ok. Our biggest problems are finding plants that survive high pH water in our area and extreme temperatures (110+ summer and occasional freezing in winter). Most hardy lillies do ok. Locally obtained reeds are also good.
As others have said, shade is a premium. Gazebos are nice to sit under but don't provide much shade in summer unless you extend them all they way across the pond. Sun comes down at a high angle here. Strategically places date palms provide good shade without dropping leaves. They can be easily transplanted at any age, but they are VERY heavy and will require heavy equipment to move even at a young age.