KRKO is in Everett, Washington. A little to the north of Seattle. It's on 1380. But with 50KW, it shouldn't be impossible to hear at some point in Southern California. Especially if you try for them around sunrise or sunset on non-directional day pattern.
I don't know if you're familiar with SDRs. Software Defined Receivers. These are remote receivers accessible online that you can tune and listen to from any point in the world. Not all of them tune the AM band, but there's a network of a couple hundred that a lot of us on this board like to visit on a fairly regular basis. Especially during winter. One of the most popular is located above the arctic circle in Norway. On that one, KRKO has been widely heard via a polar signal path during the months long arctic night. I myself have snagged KRKO on the arctic SDR at least a half dozen times.
If you're not familar with the SDRs, I'd be happy to send you a link to an interactive map. Then you can just click on whichever ones you want to try. (Note that the Arctic SDR is typically offline during the summer months. There's nothing to hear during the months of 24-hour daylight anyway.