Hey Susswein, I have a friend who did a trip through Africa last year.
You might also want to check out the Overlanders Expo held in May each year down in Flagstaff. We'll be attending in 2014, as we wrap up our circumnavigation (starting in Alaska and coming home to SC). Looks like a lot of good folks to network with on trips like you want.
The dude who did Africa is Joe, and his team name was Shoebaru--he took two $1000 Subaru wagons from England to South Africa. Team Shoebaru - 2012 London to South Africa Charity Drive
Next on our agenda is a PanAm run, in 2015. If you aren't on HUBB already, there are a lot of overlanders there, in addition to the motorcycle types. And there's a FB page for the PanAm '15, but not much planned yet.
Africa is not exactly on our radar, at least for the time being. Looking forward to running Central and South America for sure!