Sorry you have had no response so, for what it's worth, over past 40+ years I spend some weeks most years in Ghana (my wife's homecountry) so have some idea of situation. Also have hopes in some years to drive UK to Ghana. With problems in Mali I have been looking at possibility of diverting through Guinea and Cote d'Ivoire and IMHO I think there's no great danger travelling this route. Of course you will always get hassle in Africa, from police, soldiers or if you think them so, rebels, but nothing that soft talk won't resolve.
Regarding visas, these have never been available at borders and it is best to get visas, if possible, from your home country, or if travelling on West Coast, at Rabat, Morocco.
Suggest you look at Lonely Planet West Africa, latest edition I have seen is 2009 but quite useful.