I ride through some sketchy parts of LA, and I've noticed the trick is to stay on major streets (for me, anyway).

On smaller backroads, the gangsters having their drunken BBQs are more likely to mess with you. With major streets, you might get a few hoodlums making idle threats, but nothing serious (or nothing that an angry yell and a u-locked fist won't scare off).

12 miles is each way is pretty harsh, though. Bummer about your truck.