Speaking as someone who lived in Africa for a few months doing contract work (safaris, people, news, everything you can think of) I think you are a little overboard. A 70-200 with a 1.4x converter will be long enough for safari work. If you are worried just get a 300 f.4L IS ($1000 used) and couple that up with the 1.4x converter to make it extra long when you need it. Any safari work you will do will be in daylight anyways.
What you need is a camera body, a wide angle, a midrange zoom and a telephoto. Thats it. Honestly the whole time I lived in Africa not once did I use a flash, and I shot in a lot of low light situations. I was documenting village life and a number of other situations where a flash would have been detracting to what was happening. Besides the on camera flash of the camera body you get (unless you get a 5D or 1D) will be enough to use for fill if you require it.
Another thing to consider, if you load yourself up with tech gear you'll be too busy screwing with your equipment to actually take in whats happening. I did most of my work with a single camera body and a 24-70. Thats it. Less time messing with equipment, more time documenting life.