Hi Elliot,
I fish inshore from Northwest for GT's..mainly around the Keppel Islands. The problem with big GTs out that way is that everywhere is a bit like everywhere else, so it's hard to find a fish holding feature. In general I would look along the southern side midway down the reef, that seems to be the deepest drop offs.
We are too far south for red bass, but there are still plenty of top water targets. As a suggestion you might have a lot of fun on a lighter popping rig, say pe3 with 100 to 150 mm poppers andsomesebile stick shads. There are heaps of smaller trevally species and reef fish in the shallows, even inside the lagoon in the very shallow water, your rig would be perfect. It's more like flats fishing than typical gts. I spent most holidays as a kid next door at Tryon Island before it was rezoned to green. The very shallow fishing is underrated, even catch some of them funny looking whiting (bonefish).
I am not aware of any deeper shoal near Northwest that is steep enough to hold GTs. West end of Douglas Shoal or Johnson Patch hold Pelagics.
Unfortunately Northwest has been hammered by the fillet and release crew. However since trevally are of little interest to the freezer stocks the light gear fishing is still good ( as far as I am aware)....still a magic spot, just wish you could not hear generators in the middle of the night.