Builder_Chris is right, you won’t be able to hold africa without US assistance. if you left all of your african forces down there, you could slow them down for a couple of rounds though
if the US is going for all out Pacific, i would still try to convince them to use whatever they have in western usa in the african theatre to help. also, i always build an IC in india if japan can’t take it feasibly turn j2. this leaves you the option of sending tanks to africa once Japan is booted off China