It's been so long since I was in San Diego that I can't offer up any recommendations that are recent. Though in the past I've had luck both on Shelter Island, & in Mission Bay. The latter is generally easier to get a big truck into, & I don't think I've ever seen a Lo-Boy on Shelter Island. Don't know that it's even possible to get one in there.
Perhaps that helps a bit? At least for narrowing down where to concentrate your efforts.
Some of it too depends on where you plan to have moorage down in SoCal. And how easy it'll be to get the boat ready for sea after launching, so that you can leave the launch dock
for your slip. As in theory you could put her in anywhere from north of LA on down to Chula Vista, near the border. And I've used a yard there too (Chula Vista), but it was ages ago. The catch there is that the south part of the bay where the yard & marinas
are is pretty draft
restricted. So if you go out of the channel, you'r in the mud. But if things haven't changed too much, they can handle an 18-wheeler no problem. As we launched an IACC boat there.