The run down from Ventura to San Diego can take 3 hours or more depending on time of day, accidents, etc. and can be darn right unpleasant sometimes. Going east to avoid traffic will take twice that or more but the scenery will be much nicer and traffic almost non-existent. I would head over to the 2 through Angeles National Forest, then the 138 east, a short run on the 10, then south through Banning to the 243 through Idyllwild, Warner springs, Julian, Campo then Tecate. A much longer route distance wise but if you have the time for this these are some of the best motorcycle roads in these parts.