Hi Duncan, one piece of info and two quick comments.
For the route, see
Budapest-Bamako - The Great African Run it's a great little site, and if they could do it, you can too! Incidentally, they recommend the coastal road, and for a good reason, it's the only route where if you break down you have half a slim chance to have some ind of assistance.
As for the bike, I strongly recommend you verify the bike of choice v. the route. I am not aware of anybody doing the PaDak in a BMW 650F, or much less a Suzuki VStrom. I would recommend a 2nd-hand R1000 GS, or even an R80 GS, THAT bike can do it, the 650F...? I wouldn't bet on it.
I believe I know the VStrom, it is a bike for city folk who want to feel like Indiana Jones while tackling London traffic.
Suzuki make (made) the excellent DR750/800, go for those. Or go for the ever-present Yamaha XT650.
But whichever bike you choose, remember:
1) If you can't pick it up when it falls fully laden off the sidestand, it's too heavy bike;
2) If you can't learn how to fix the most basic things by yourself, it's too complicated;
3) If you don't like top-heavy bikes, don't go for big singles/twins, go for a flat twin.
4) What ain't there can't get broke - go aircooled, shaft drive.
Am I saying "R80GS"?
Regards,
Maurizio from Rome, Italy