There should be something here to suit most tastes, I'm confident these are all guaranteed Dad pleasers.
Send Fresh fish
San Diego's premiere seafood supplier - both wholesale & retail. And while I'm not necessarily suggesting you give a gift of a side of fresh salmon (though you could) - their website is perfect for sending seafood gifts anywhere in the country. Imagine your recipient's joy when they open a gift of Baja Yellowtail, or huge white Mexican shrimp, and the list goes on.
Specialty wholesales fruit, produce and tons of other stuff to pretty much every restaurant in San Diego, but regular people like us can go shop there - which I do pretty much every week. But they also have a great collection of local, San Diego products that are perfect for a San Diego Centric gift. Sauces, jams, charcuterie, mustards, oils etc.