Welcome back dutchyankee. You have not been around so much, and have been missed, you probably spotted the pretty unpleasant interractions going on in some of these threads.
About crew rest in some locations, well Lufthansa/Brussels Airlines fly into Senegal, Gambia, Sierra Leone, Burkina Faso, Liberia, Ghana, Ivory Coast, Togo, Benin, Cameroon, Congo DRC, Angola, Burundi, Rwanda, and through triangle routing crew rest in places acceptable to crew/unions.
Air France also flies to most of the same places.
I am not saying that BA/VS ply all of these routes, but it does show some are quite fine. I have friends who work for BA who would have no problem with some of these places, indeed would request them. Triangle routing also saves jetfuel costs if you are not aiming for local traffic rights.
Further south in Africa, this becomes more difficult, due to flight length, flights at reasonable hours/decent utility of aircraft etc.
Harare is probably not yet good for crew rest, but a stop in Lusaka or even Kigali would be fine for such purposes, maybe using a day room as you indicated.
I recall your post about JRO not having decent sized hotels, but as you say, this could be part of a routing that served Kigali, Dar or Zanzibar.
Maputo is capital of a major Natural Gas producer, so I am sure of interest. BA/Comair does now fly there, but Joborg, with its famous baggage theft situation, is not an ideal transit place in my opinion. I wonder if a stop in Durban woud be ideal, for both BA and Comair, the routing being LHR-Durban Maputo and v v, maybe on 772 or 787.