Not to be rude, but do you understand the sheer size of Africa, and how many different states it holds? Logistics are a total nightmare, when your question reads as if you are only thinking of distances, not of bandits, roads that are much more potholes than road, predatory officialdom, and so on, and on.
Start by meditating upon why airplanes are used in Africa in the first place, when that is often because of the risks of travel by road. We used to fly a sector of 19 minutes, between Warri and Port Harcourt, just because of that. I would love to see the adventure that would ensue, trying to get one lousy little barrel of Avgas down that road, so that if you make your film be sure to tell us where to go to see it.