Hi JNS101879,
You really are out in the middle of nowhere when it comes to mattresses 
The closest possibility I could see would be in Yuma …
Denver Mattress® - The Easiest Way to Get the Right Mattress They are a factory direct regional manufacturer that has a wide range of mattresses but one of them is the iChoice which is a mostly Talalay latex mattress which has a separate Talalay latex topper.
http://mattresswarehouseofyuma.com/id4.html Yuma, AZ. They carry Stress-O-Pedic and Sherwood and neither one has an all latex mattress but they may have a latex hybrid on their floor. If you decide to go here I would call them first to see what they have on their floor and to make sure that there that any “latex” mattresses they carry have more than just a thin layer of latex mixed in with other materials.
Other than that the San Diego list would be your closest source of latex that I can see and there is a much wider range of options there.
Just for reference as well … post #7 here has more about the difference in “feel” between Talalay and Dunlop.
If I was in your shoes and I was taking a drive anyway I would probably head in the San Diego direction because of the wider range of choices but if you do decide to order online without testing any latex first then a good return policy may be important just in case you are one of those that doesn’t like or prefer the “feel” of latex.
Phoenix