Are you on one of the overnights between US and SA that land in Dakar for gas/food/crew change? That's a pretty late arrival!

I've never gotten off in Dakar - so I can't provide any recommendations - but I understand from some of the crewmembers on US-SA flights that there isn't a whole lot (by, I guess, the crews' standards) outside the airport. I seem to recall one of them telling me they basically bring their own food with them to wherever they stay.

By your handle, it appears you may fly to/from Africa frequently enough (and perhaps on US carriers' planes) that you may be in a position to ask the crew where they stay, if that place is available to travelers, etc.