Working in Ghana, I have the same issue but decided not to bother Adcom until I actually have an invite.
But I checked options anyway: From Accra I can either head for London or Dubai.
From Abidjan I assume you're best bet will be Dubai as the connections to London are not that good (at least thats what I remember).
Sao Paulo is no option from West Africa despite "geographical proximity" - there are no direct flights. You can only go via Europe or South Africa.
I am really wondering if they considered alternative solutions for applicants from remote places...