I know that Europeans regularly take RVs to destinations in northern Africa, particularly the more stable locations in northwest Africa, and there are rental programs and caravan tours in South Africa and on up eastern Africa toward Kenya.
However, most of the East Africa tours I've looked into use air transport from urban area to urban area, country to country. In terms of road networks, infrastructure, and red tape, it is not the same as renting a RV somewhere in western Europe and driving all over the continent.
Just Namibia and South Africa would be a good start, and is pretty common as a tour these days.
Tom Test
Itasca Spirit 29B