If you haven't done so already, check out the rules in the " oneworld awards using American Airlines miles" sticky. There's immense flexibility on routing derived from this:
When determining the "total countable trip miles" of an itinerary, the only relevant cities are the originating city, the stopover cities, and the city in which the itinerary ends.
If you don't mind and have time for odd routing if needed then I imagine you'll be able to make a booking given your +/- a few days flexibility. I worry about your HKG-JNB somewhat though - others will know better but the indiret route is very indirect (via bcn, mad or lhr) When will you have enough miles?