I've done several safaris and have never had a problem with my Thinktank Airport Accelerator fully loaded with D7000 & D80 both with battery grips, essential when opportunities for charging is uncertain. I've also had a soft case for clothes!
I do not think a monopod is essential unless you are planning lots of walking as there are plenty of other ways of steadying the camera using the vehicles. I've usually kept a long telephoto on one body and a wide angle or my 17-55 or the other. Essential for not missing that shot by having to change lenses. It's surprising how close you can get to some of the animals. Also I try not to change lenses when on the road. The red dust of Africa permeates everywhere!
Personally I would take all the lenses. I'm way at present so unable to check but I suspect most of my shots were in the 50-200 range with a few at the extreme of my reach which is 400, if that helps.