Ralph over at the Wargaming in Central Oregon blog has been in contact to let me know about his fantastic East African campaign using Irregular Wars. He already has Portuguese, Zanj (also can be Omans when camels/horse included), Interior Native, Ming and Ottoman armies painted up, with Abyssinians on the way.
In the photo above, Zanj forces (left) launch their attack on the Portuguese of Lord Renaldo (right). The blog is well worth a read with characterful battle reports that draw you in and create a great little narrative.
If you are interested in the flow chart he uses to streamline campaign decisions and resources, it can be found HERE.