Just taken a look at the history of TREK Airways. They commenced operations in 1953 and continued Viking operations until 1958, replacing them with DC4s. They operated three Vikings ZS-DKH, -DKI & -DOU. Some parts of -DKH have survived and they are in the SAA museum.
They were the only airline who operated Vikings from SA to Europe but Vikings were well known on the "Africa run". Central African flew from Salisbury, then Southern Rhodesia. Airwork and Hunting Clan Air Transport flew from Nairobi.
Not too sure how long the flight would have taken to SA. Airwork took two and a half days on the Blackbushe to Nairobi route, that included two night stops, normally Malta and Khartoum. I guess TREK would need another night stop and take a total of four days to reach Johannesburg.
http://www.timetableimages.com/ttima...b/tre50sb1.jpg