Phil Rutter (Mark took his Woody Agriculture Class) talks about this in an interview with Diego who lives in CA. Part 1 is
here but that discussion is in part 2. He's optimistic that the genetics are out there for Chestnuts.
I don't think Hazelnuts can handle a hot environment. Phil is coming out with a book on Hazelnuts this fall, and was interviewed
here.
Depending on your goals, you might focus on what does grow in a hot environment - pecans?