We all get in on July 13th. It does not look good for the posh hotels, so right now the plan is to get them out of customs clearance and talk/catch up... By 9 pm they will start nodding off, so it will be time to pull out their sleeping bags and sleep in a chair or on the floor. Two of us will sleep and one will watch.
As the SAA flight leaves before 6 that means check-in will start just after 4...
We shall see. OTOH, the ACCOR hotel mentioned earlier (at 400 ZAR) is a definite possibility as they will allow 3 in a room - if the sons (both adults) get thru customs fast - a warm shower/bath is really relaxing and really helps a quick sleep.