I cheat a bit
I have to say, I do cheat when it comes to fly fishing for kings/blackmouth. I do fish for them from the beach, but I watch for exact conditions stated. BUT, here's how I cheat.
Most good sized blackmouth sit deep. And this is from a boat mind you. I use a mixture of conventional with fly. I have my fly rod set up with a sinking line (and big reel with LOTS of backing). I then set up my leader to lay in my downrigger. No flasher, just the fly to line. I then drop it down to depth (depends where I'm at, but sometimes up to 160'). Then, slightly troll. I watch for my flyrod to go off, or stay on a dead drift and do a quick yank to release the line from downrigger. Then do a quick strip, stop, and let line fall. Has put me into some nice kings. May be unconventional. But has worked for me. When I get my new boat, will have to take some of you out to see what I mean. Works great, I call it "Fly mooching".