Liability insurance is required in most countries outside of Europe and in most cases this must be purchased locally (at the border, for example). However, taking out comprehensive insurance from a specialized travel insurance provider is the only way you can insure your vehicle against damages or theft. Tourinsure, for example, provides specialized international car insurance, as does Clements Worldwide.
Belarus, Russia, Morocco, and a number of other countries participate in the “Green Card” insurance cooperation (view a list of eligible countries here: http://www.nbi-ngf.ch/de/nvb/dokumente/gruene-karte).
However, as you mentioned, many Swiss insurers do not include coverage for those countries (for example, the RUS or MA abbreviations on the green card may be crossed out). Ask your insurer if they offer a supplemental insurance rider covering those countries. Liability insurance is obligatory for cars entering Russia, and if you are unable to get this from a Swiss insurance company, you can take out a temporary Russian policy at the border.
In West Africa, liability insurance is obligatory. You can buy insurance in the form of a “Carte Brune”, which you should be able to purchase in Morocco. This certificate of insurance is valid right across western Africa (Mauritania, Mali, Cameroon, Congo, Guinea, Liberia, Nigeria, Senegal, Sierra Leone, Togo, Benin, Burkina Faso, Côte d'Ivoire, Gabon and Ghana).
The COMESA “yellow card” can be purchased at your point of entry and provides liability insurance in the entire southern african region and most central and eastern African countries.