White Rose -brilliant
go with Mike at White Rose - he is absolutely great!
It's that simple...
for the rest, just spend some proper time on your planning (lots of google earth, jeppesen and lonely planet!). Our biggest headache was Sudan, but we still managed to track down an avgas source at Khartoum, and Mike sorted the clearances...
What I would say, is that it is MUCH easier than you think. Also, perhaps of interest, 1 Maule and 3 pax Brussels-Cape Town cost approx GBP18K over 20 days (this in an owned aircraft, no servicing/running costs calculated).
Safe flights, Sam.