MPM-MPM (or ending elsewhere in Africa other than SA or Mauritius) should be OK if you can book it. Rule 4E3 whould not apply. Just that last JNB on your itinerary would have to change. Then add a flight to South Africa if you want to visit there. I'm pretty certain the skeleton coast would also work and be bookable. I am anxious to see if anyone can book from MPM. I might give it a try when I get some time. Good luck to you--anxiously awaiting report.