What types of aircraft are rated on? For the C206, which are mostly turbo charged you could try Carletonville. They asually have two aircraft flying. Or you could try Witbank. There is an operation north of Wonderboom that uses C206's otherwise you can try the PC6's at Wonderboom itself. But if your'e not rated, forget it!
Its a bit of a drive, but if you make the trek they'll see your'e serious and if you have the time and the rating to boot.....