New to Bonsai from the very hot southern California desert

[DDOZ]

So - new to Bonsai here in the Desert in beautiful Palm Springs, CA. Going to start with the philosophy that if it can grow in my front yard when it gets 118 degrees in the summertime, then maybe it will also work here as Bonsai. Several things here seem to be nearly impossible to kill that I'm going to try - first is Bougainville as I have about 6 large bushes in my yard that are all about 20 years old and have nice, good trunk sizes. Already started to try to thin the branches out a little and they sprout new shoots almost immediately. Down side is that they have been trimmed all this time as yard landscape bushes not for Bonsai and have a seriously dense mass of branches (and very long thorns) going all different ways in the middle. Thinking on waiting a little longer for the temps to drop some before I try digging any of them out of the ground. In the meantime, am starting by trying some cuttings and air layering to see if that will work. Any advice for very hot dry environments is welcome.