You're right there LBD that you'll get the most out of your lures when you tie the leader directly to them. Damn straight. Every movement of the line and rod translates to the movements in the lure. But of course it's an issue when you want to change your lures regularly.

When you start adding split rings, swivels etc. it creates loose points of movement, making it not as effective for working sensitive lures. In the picture below you show multiple loose points of movement; from the split ring to the loop, the swivel to split ring, the swivel itself and the swivel to the thimble, all creating loose points of movement in your connection to the lure.

As you state the "standard practice around the world" in using swivels this way is not for the swivel to be an essential twisting part of the connection, but rather for the swivel providing a point for the split ring and leader to attach to. Poppers don't mind swivels too much but sensitive floating stickbaits do, which are the best in my opinion for targeting kingfish. If you run a thimble, a grommet or plastic tubing, there is no real need for a swivel. And if your lure is swimming right; not spinning, there isn't going to be any line twist. So why use it?

I was privileged to have a somewhat broken conversation with Konishisan a few years back about connecting topwater lures, where the summation was No Swivel = Good, Swivel = No Good.

Yeah Zac I'm simply not experienced with the rod but have two charters booked for next month so hope to learn more about my gear & this style of fishing in general. Good to hear an encouraging voice & will update this thread once I have done the charters. Hopefully with good news & maybe some pics.
Cheers Pete