Engine work or boat repair? I have been living out in the murrieta/temecula area for over 20 years and have always had to drive to San Diego to back in day, blue porpoise marine or to seawitch in vista. There is a guy in wildomar called action motorsports who repairs boats and motors but I have only had him install a keel guard on a small whaler.
Think either way u gotta make a drive. For me, I prefer to travel down south.