What is the full stock list, with rough sizes? This is important, because the tank is almost perfect. You don't need to add any rocks or driftwood. You don't even need to move any rocks or driftwood.
There is one, and only one, perfect way to balance this tank. You need to add a single Stingray. Something black with big white spots, or a nice Marbled Motoro, or some sort of crazy hybrid,