Hey Monkey kiter,
The beach are right in front of the GRSC is generally sheltered in a Nor Easter. I'm talking about the next point down, there is a small swimming enclosure a few hundred metres South West of the GRSC. If you rig up on the point where the river narrows the most, you will find it very good for kiting.
The sand flats upwind (in NE) of STGSC are OK in Southerly (although onshore) but are all cross offshore in a nor easter. Stay up on that point and you'll have joy! From memory I think it is Lena Street off Clareville Avenue, Sans Souci.
The reason no one kites there is because no one kites there. Once upon a time, I started kiting at Dolls Point where there were no other kiters, thats when everyone used to kite at President Avenue car Park, Brighton, now look at it! Someone has to be the first!

Might as well be you. You could call it Monkeys Point!

Cheers and have fun.