I would try to stay along the I15 corridor myself, as when the LA/OC/SD mega city finally finishes it first direct connection it will be along this corridor is my belief.

Anyway I think it is only maybe 15-20 years before this corridor gets built out
( Darn near completed it last boom).

(Of course it may happen along the 215 corridor first but I will refuse to recognize this as being the first true connection that establishes an endless city from the Mexican border to Bakersfield).