Thanks TUEDV7, I used some local resources in the mean time got a way better offer. As it is a business flight, not touristical, I need a smooth operation without problems passing security etc... From what I hear we might be there more often in future, so I bite the bullet once to get familiar with the place and will then most likely follow your advice.
Just as a side note, I found the Ghana CAA hard to communicate with, at least several of my mails went unanswered, as did mails to Kumasi apt, but thats because the email address in the Jeppesen is wrong.
Thanks again,
h_d