I used to be from the Southern part - long time ago. I loved growing up in Southern California in the early 60's. But, I must admit that now I avoid the Southern part, except to see family, or once in a while on business.
I went to the county with a well written reason - the truth. Work late at night for part of the year. In addition, travel with sample case containg records (not valuables). I had been turned down previously (late 70's). I think (but I am not sure) that I received my permit because during the oral interview I was straight up, and answered the questions in a manner acceptable to the officer. Another factor, extensive personal training and qualifications - range master, etc. I'll never know, but I did receive the permit. I think one factor that may help in any application and interview is attitude.