have you ever tried riding one of those private mexican buse lines? i think if anything those buses would avoid any stops where there are checkpoints since the majority of their bus riders are hispanic and undocumented. in my case i have taken the private mexican buses back up to northern california for winter break, spring break and summer break from los angeles (san franando valley) with out any problems. and also the fare might be cheaper as well i saved $25 dollars by using them instead of greyhound. but ive only traveled once going south from the Sacramento, CA to San Fernando, CA with stops in stockton, modesto, fresno, and bakersfield with out any checkpoints.