Hello - I'm in Needles, CA - about 90 miles from you. I have many of the same gardening challenges that you have in Vegas, except our soil is better because this area (on the Colorado River) was all river bottom 100 years ago. Still, the heat is the biggest challenge in the garden. I liked meancoyote's suggestion to use large containers with potting mix. Probably your best bet. Now I just have to find seeds for "Jerico lettuce" and "Malabar spinach".