Last time I went to Rosarito (just south of TJ) for fun; they almost didn't ask me for ID!! We came back fom chillin on the beach late Friday and waited in traffic for an hour to cross. They were basically waving people across. Ditto the previous time and I walked across. They didn't even look at my bags!!
I've heard to take a friend (female is best), go do your thing, change shirts and put on a hat (to change your appearance), and go chill at the beach or bar. Definitely drink before crossing (chill out and a little beer on the breath lets them know you were down there for fun-don't get pulled over for DUI however). Take a beach bag or golf clubs. Make it look like your were down there for a siesta.
Good luck!!