I fly this route monthly with work and i suggest you think long and hard before you go... I have 4 engines and shed loads of petrol, and it is still a very barren 6 or 7 hours between europe and Zim, Zam and SA. I am sure it can be done, but there are thousands of miles, where if you come down no-one is going to come and get you. but if you get it done then a trip of a life time! I would guess that 400nm south of tunis/tripoli area to about 400 nm north of Lusaka will prove tough to crack..
Good luck