I am only guessing as I have never fished there, but I would have thought about a kilometer away away from the mouth would be a little more productive for the more desirable species.
Usually around most mouths you get all the bait like mullet which bring in kahawai and trevally followed by good kings. But further along the beach on the edge of the eddy ( still water ) where the inner bar comes to an end, fish like snapper and gurnard would be more prolific.
Slidebaiting directly into the channel would be worth it too.