G'day mate.
I fish the gold coast regularly, and there are thousands of spots where you'll catch fish. Basically any jetty / bridge / pontoon /rock wall will hold bream, and most sand flats (they are everywhere) have flatties. First place I'd try is under a few bridges.
The main problem I had when I was land based was getting HB lures into good areas. I had some success fishing from rock walls, and retrieving the lures (hard bodies like sx40) parallel with the wall so it dives and swims along the length of the wall. This gets it deeper amongst the rocks where the fish hang out.
Also, your hard body lures are a good selection and I have the same ones. Throw the switchblades at bridge pylons and let them sink before retrieving. They also catch whiting and flathead on sand flats.
I find that SP's are much easier land based, because they cast further. Try about 3" plastics (minnows or prawns) on a 1/8 oz jighead (or 1/4oz for further casting). There's tons of info on here about retrieving plastics - just make sure you let the lure sink to the bottom before retrieving.
I'm not a trevally catcher, sorry.
Good luck