@VilageidiotxHmm. Yeah. I like that sort of idea - I don't want to go totally, secret-secret divide and conquer. I read that what German colonies were, had a more merchandile approach to them.
The Germans minority/nobility would want a nice living, but wouldn't be overly dick-ish - since they know, they'd be heavily outnumbered. Some members of the Yoruba/Duala could maybe be part of the nobility? As maybe black gentry - back when their forefathers served in the Colonial armies and were rewarded for their loyalty?
And yeah - the rural parts could remain rural. Maybe having some mines or an oil-well or two. The usual aid-package or local economic boost to please the usual chiefs. But if they want remain rural - they can do so.