I live near there...and see several train buffs with cameras and tripods set up on hwy 138, about 2-3mi east of Interstate 15.
In case you are looking for another spot.
Railfan_Bill wrote:
I venture to Los Angeles once a month from Las Vegas. I stop at Cajon Pass to shoot (photograph) trains. Seems the RR cops don't see that sometimes. These are some of my efforts.