Its not a car, its a plane and almost all the a/c on the SA register are ex USA and in fact, there are a lot being advertised in SA that are still on the N register. Sefofane has bought all its caravans in the states and flown them to Bots or Nam as have a million other operators in the area.
Do your homework and you will find the way to get it done. If I were you I would start by contacting some of the aircraft sales companies in South Africa and ask them how they do it. Try aero export, they export a/c to RSA ex USA, foster aero,placo to name a few. contact them and ask how its done, hell they may even buy the a/c off you! Also try contact the charter opperators like Sefofane, Mac Air, Zambezi air, MAF, Airserv Uganda, delta air botswana, and a number of others in Namibia, they all have aircraft that they have imported and may even want another one.
Good luck and if you get it right, let me know, I would love to do a flight like that!
Dog