South Africa to Tanzania | Planning help needed
 

Planning a solo (high possibility of a 4x4 tagging along with 2/3 non-riders) ride from South Africa to Tanzania.

From: Jo'Burg, South Africa
To: Mara Region (Lake Victoria), Tanzania
By: Motorcycle (Yamaha Super Tenere)
When: 2020 (I know - still a long way off!)
Purpose: Adventure with a fundraising factor added in - in support of multiple vocational training centers & primary medical care centers for underprivileged and handicapped youth in my home town in Tanzania.

Looking for ideas on:
routes,
best time to ride,
how to build a good fundraising 'program' and
everything helpful to make this ride a reality and a success in its purpose.