I believe Africa can become much more profitable for Germany if the UK fails to re-take Egypt in UK1.
This happened the last game I played. In G2 I took transjordan, and then in J2 I was able to sneak a japanese AC through the suez to link up with the German BB and transport. I then landed some German fighters on it, and this little fleet survived for a long time.
If the UK or USA want to waste their airforce on it all the better.
If they try to send ships through the med to come get you, smash them with your BB, trans and AF. Following that, move your jap AC to southern europe and then buy another transport on your next German turn.
To me, the key to making Africa profitable for the axis is to not engage the allied reinforcements marching along North Africa. Resist the urge to fight them and preserve your forces. After taking or re-taking Egypt, fan out and grab as much territory as you can. However, try to keep most of your forces, and certainly your lone tank, outside striking distance of allied transports floating off Algeria (ie stay mostly in Italian East Africa, Rhodesia, or South Africa - do not even bother with french west africa).
The best African outcome for Germany is to own parts of sub-Saharan Africa with Japan focussing on trading Egypt. If Germany’s fleet is still alive, provide support by landing token forces in either Egypt or Transjordan, whichever is safer.
If you do decide to make a stand in around G3 or G4, turn Egypt into a deadzone. This can be hard to do as you will need to make sure most of your Airforce is in either Southern Europe or the Balkans the round before as well as having most of your land forces in italian east africa. I would only suggest doing this however if there is a gap in the allied reinforcement chain marching along north africa.