When I've travelled to Lagos, I've just used my FNB Visa credit card. It was accepted at all placed I tried to use it. It did sometimes decline when they used a "local card" speedpoint, but then they just got another speedpoint machine and then the transaction went through. You'd earn ebucks at twice your normal rate which, if you're on RL5, makes up for the "buy rate" and FNB 2.75% commission.
I'd also take some small denomination USD notes for gratuities or small items. USD are accepted everywhere. I've used FNB forex delivery with no impact to my Reward Level.