You don't need a visa for just ppl level flying in SA, just like you wouldn't need a visa if you'd decided to go there for some scuba diving course, private flying is 'holiday', but if you're that worried about it you'll have to phone the embassy, but then the answer from them is going to depend on the exact words you use in your question to them! If you phone to ask, just keep it straight and simple. If you say this is 'module one' of many in your grand business plan to run an airline, I can see they might think twice, but PPL flying for PPL flying's sake has always been 'holiday'
What you DO need is a whole blank page in your passport for their entry stamp. They have refused entry to someone frequent world traveller without a whole page blank, even though there was room for the stamp. You'll probably be expected to have 6 months validity on your passport too, although you might get away with 3 (another question for the embassy if that applies).
You'll enjoy PE and Algoa