Belief is one thing, but perhaps it would be worthwhile to check out this website which shows a list of 24 places in California that sell ethanol-free gasoline:
I have been to the Sinclair station listed in Indio, and can confirm the past availability of their ethanol-free 110 octane Mogas. It’s spendy, and the 100 Octane stuff at VP fuels in Paso Robles (in SLO county) may be even worse, but ethanol-free Mogas is certainly available in California.