It's much easier for BYU to get its way in a largely LDS community. BYU isn't like other schools that have a more distinct separation from the local community and its policies. Having an overwhelming LDS population that lets BYU have its way would be necessary. Plus the students would need an area with low cost of living and plenty of room for growth and customization.

SoCal would be far too expensive. In some parts of AZ you might have high enough concentrations of LDS members to pull it off. Otherwise it would still need to be in Utah somewhere which would seem rather odd.

Or they just pick a small, rural area (like Rexburg) somewhere in Texas, walk in and take it over. Within a few years nearly everybody would be LDS and the church could practically build a community from the ground up.