You don't need to go into Maputo (unless to check in?). The anchorage in Inhaca both inside and outside are safe depending on the
wind and have good holding. You can still get very strong winds 60knots plus from nowhere even in season. There is no shelter between Richards Bay and Inhaca.
The biggest issue in the Mozambique channel between the mainland and
Madagascar are the gyres, see currents Windy.com
There is very little south of Mahajanga (officials there are very welcoming and proper). I have only sailed south from there so needed to cross and stay close to mainland. I would assume you would need to be on the
Madagascar side to go north. Sailing up the coast to the northern tip should be fine local sailing
boats do it on a daily basis.
The seas and currents north of the tip are vicious - best of luck with that bit trying to go north and east.
Any reason not to wait for next season?