You may be lucky to find one. Many years ago Kenya cynically forced all commercial aircraft operating from the country (a great many on vital international humanitarian and aid work) to re register as Kenyan, as well as some non commercial aircraft (corporate/private) that they incorrectly chose to view as commercial. This was done, I believe, to allow them to be heavily taxed. Nice!
I don't think there will be (m)any N reg aircraft in Kenya at all, let alone for hire.
Hope I'm wrong though.