In none of the places you listed is there a large population of LDS who can, as the OP wrote, attend, staff, and support the institution. The Salt Lake Center is primarily there to support people in the Salt Lake Valley who can commute to it.
The Mesa/Gilbert area is the largest community of members in the world (not currently served by a CES university) who live within a reasonable commuting distance (like a 25-minute drive) of a potential campus. If you're thinking of the Los Angeles area — that's not a reasonable commuting distance.
A satellite campus of BYU (like the Salt Lake Center) is the best option, because it would allow BYU (no hyphens) to increase enrollment, and give people (in AZ and Southern California especially) an option other than BYU-I that is reasonably close to home. But it would attract people from all over the world as well. And BYU could start accepting some of these 33 ACT, 3.9 GPA people it currently rejects, as well as a lot more of the 27 ACT, 3.7 GPA people it currently rejects.