Sadly, I’ve never gotten the chance to fish San Clemente.
I can give you some general bonito tips. Live bait is best, but if you know an Asian food store that sells fresh frozen anchovies, get some of those. I don’t know the Bonito size they are at San Clemente but if they are pushing #5, you are going to need a setup with #20 test line. To make it simple and easy, use a spinning setup with #20 braid or more with a #20 flouro leader. Fly line the bait on the surface with a split shot to keep the bait down. Keep the bail open, while lightly holding your line. When the bonito picks up your bait, quickly let go of your line and count 5 alligators, close the bail, and then set the hook.
If the bonito are hitting “Irons” like maybe a megabait, I like #20 mono on a casting setup and a 1-2oz jig.
You can also do a casting setup with #20 or heavier braid and throw a hard bait with a diving lip.
The wooden ball and feather technique (wooden ball with trailing hook with feather far behind) can work too but it’s my least favorite way to catch them. I like the feeling of dead sticking a fish and ball and feather doesn’t really give me that feeling.
Hope this helps. I didn’t want to get into complicated details. If the bonito are smaller, you may have to drop down to #10 test.
I like to use a simplified trolley rig off the piers. First I attach an at least 4 oz pyramid sinker to my mainline using a snap swivel or tying it directly on. Then, I cast only the weight out as far as possible, let it sink to the bottom, then give the rod a couple of light pulls to anchor the weight before leaning the rod against the railing or putting it in a rod holder and reeling the line tight. Then I make a 3-4 foot mono or fluoro leader (preferably fluoro), tie a size 2-2/0 hook (depending on bait size), on one end, and tie a snap swivel to the other end. Then, acting quickly, I take a small-medium sized live bait (anchovies, sardines, and small chub mackerel work the best), hook it just below the dorsal fin (in between the dorsal fins just below the skin for mackerel), clip the leader onto the mainline, then let it slide all the way down to the water. If the bait does not immediately swim out, I take the rod and give it a couple jerks to liven it up/allow the leader to slide further. I haven't fished San Clemente at all, but if there are reefs/snag points, I would tie a large (emphasis on large) barrel swivel on the mainline, then attach the weight using a section of lighter line and slightly less secure knots, preventing the entirety of the rig being lost in the event of a snag.
When fishing this rig, watch the rod tip in order to monitor the baitfish's movements. If fishing exclusively for pelagics, change out the bait once it stops moving for more than 5 minutes. If you don't mind catching bottom fish, you can choose to leave it out as long as you please. When a fish bites, generally you won't have an opportunity to let it chew on the bait as the leader will be perpendicular to the mainline, giving no room for horizontal motion. Most of the strikes using this method will be aggressive as the bait will be swimming frantically close to the surface, triggering a stronger predatory instinct than a simply flylined bait.
I have caught bonito, large mackerel, barracuda, and even small yellowtail using this method. Sometime when the bait dies and drifts towards the bottom, bass, halibut, and other bottomfish will come and eat the bait.
Yes, the sliding bait leader, as discussed in PFIC, 2nd., is a good leader for bonito and other species. One tip: hook your bait behind the collar and most will stay near the surface, hook it through the nose and they have a tendency to dive deeper in the water. A little deeper water is usually better for bass and, depending how deep it goes, for halibut. For some reason it’s not a leader that is used as much today as previously. Perhaps that’s simply because fewer anglers take the trouble to acquire live bait. When I was young, just a FEW years ago, many piers sold live anchovies and brown bait (small white croakers and queenfish) on the pier. Today no pier is set up to sell live bait (anchovies). But, it’s usually not to hard to catch some small mackerel, smelt, croaker or perch.