Regarding the Ottomans and the general gameplay, here's what I am thinking. Make the colonies not part of any one bonus but part of two or three bonuses, depending on the circumstances. For example, Egypt was an Ottoman territory for most of its recent history until the British nabbed it from them. So give it stripes and let it provide a bonus for either an ottoman or british player.
As for Turkey's 'colonial' past. Everything south of Anatolia was generally regarded to be 'colonies' of Turkey. The Arabs and Egyptians viewed Turkey as a foreign occupier once Nationalism reached the middle east. Persia was never ruled by a foreign power. And the Ottoman Empire had a very strong relationship with eastern Africa, such as importing slaves from Mozambique throughout the 19th century. To ignore Turkey in a Colonial Africa map is a big mistake in my opinion. The only time they were excluded from the continent was the last quarter of the 19th century and after that European rule in Africa didn't last more than 50 years.
As for West Africa, I know what you mean. But you could throw Liberia in as a neutral, which it was, and for the other smaller colonies, perhaps use them as connectors for sea routes along the west african coast? It's pretty much how they evolved.
To be honest, I'd like to see the more independent Africa nations play some sort of role in the map. The Ethiopians beat the Italians a number of times and were only under Italian rule for less than ten years around WWII. Tripoli was a major independent power. The Ashanti and Zulus beat the British a number of times and I know the French met some defeat in West Africa.
The trouble with maps of Colonial Africa is that the map does not portray reality, despite what the British or French cartographers and politicians wanted people to believe. Both then and now.
One possible option would be to do the wars of decolonization, but then you run into trouble with places like Guinea-Bissau being one of the most heavily fought over areas and places like Egypt just being given up. It's kind of why I went for the WWII Africa map because it was the only time in history where the powers actually warred over all the boundries they'd drawn up over the continent.