Platapus Park, with BBQ, and ok playground that is shady with trees all around. Small basket ball court too. No toilet facilities, so I guess people pollute the reserve, and waterway.
There is a couple of rather small picnic areas within Caboolture South itself-
Penshurst St, Caboolture South
Barossa Cr, Caboolture South
However a 2 minute drive or 10 minute walk up Morayfield road and you will find centenary lakes