Best route down to Cape Town

[BlueAbyss]

I am planning a RTW trip, starting in Australia in February, up through south and central America, then over to Europe. This final leg involves riding from the UK down to Cape Town (between the beginning of August and the end of November) before the bike is popped onto a boat back to Perth.

My problem is Africa. I would dearly like to come down through Turkey, Syria, Jordan and Egypt and head south, but despite hours spent poring over the HUBB and other resources, I cannot seem to find a suitable route coming south out of Egypt which seems do-able (Sudan-Eritrea-Djibouti-Ethiopia-Kenya or boat it from Egypt to Djibouti).

Another option could be simply to take the western route through Morocco, Mauritania, Senegal, Mali, northern Nigeria, Cameroon etc.

I also am very aware that I need to be getting my carnet organised soon. Can the eastern route be achieved sans-carnet? What's the situation regarding South Africa?

Regarding visas; I have two UK passports, so would be to have leave one getting a visa whilst travelling on the other.

I am aware that the situation changes on an almost daily basis, but would be grateful of any advice.