Everyone will have a different view on this question. The best info i have found is on the ADAC site, the important bits are in english. You can download a pdf file that shows their current information on all the african countrys requirements. That shows that some of the countries you want to visit will certainly want a carnet. These guys are the main automobile accociation in Germany. They issue carnets requiring less of a bond/guarantee than RAC which makes a carnet for Eygpt for instance more affordable. There have been several posts on this site of people who have used them instead of RAC. Check out previous posts.I will certainly use ADAC on my next trip.
There will be a few guys who will say you could do this trip without a carnet. My advice is get one.
Have a great trip DB