I'd consider YVR-JNB or YVR-CPT. $3300 CAD in P, $3900 CAD in Z.
This is part of the batch of recent YVR-Europe deals so the ticketing deadline is today.
Here's a currently bookable example with P in one direction and Z in the other:
30k SQM as above with the P/Z combo.
Same day turn is possible. Far easier to do that in Z than P, and I think the best possibility exclusively in P is the week of USA Thanksgiving. Fare allowed stopovers until 2 days ago, unfortunately no stopovers in Europe now.
Works on Google Flights, and also works on the AC website (though both can be unwieldy with this fare).
Can add many more flights for more SQM.. but it quickly gets grueling. Alternatively, if you need more SQD in this trip specifically, I'd consider searching for TK between CPT and IST (books into TK Z) as it adds ~1k in YR.
Edit: I wrote most of that after having misread your departure airport as YVR. Note this also works from YYZ for both JNB and CPT (everything is ~200CAD cheaper).