Hi Max
Only a handful of people have gone this way in recent decades: trans Af has become either west side or east, the 'Y' meeting in Zambia.
And now it seems, west side only.
Trans-Chad and Darfur to Sudan is still perceived as risky. (Escorts or fly over Darfur).
Eastern CAR and South Sudan have been unvisited or closed for tourists, same with the vast feral regions of outback DRC, the main overland route in the 70s and 80s. The worst might only be a robbery, but that can still be stressful.
Right now getting to Congo-Brazza is no harder than it was.
From there you might try and strike out east the 1000 miles to Uganda.
Even in the good years there were famous pictures of churned up mud ruts deeper than a truck was high.
Insurance, an IDP and other paperwork will be the least of your worries.
Obtaining good fuel and not getting sick will be what counts.
Much depends on your previous experience in Africa (if any), your appetite for raw adventure and ability to get out of a fix or handle threats.
For most, the established overland routes (especially the west side) have moments which are challenging enough. Prolonging the tension is only for the brave, and they rarely appear on the internet ;-)
As I said elsewhere, as pressure for trade and travel builds up, the 'river' finds a new way around. DRC may be it. Eastern CAR; I don't think so.
Otherwise, stay west and come up to Moshi from Zambia. The notorious 1000km track from Kinshasa to Lubumbashi will give you plenty to chew over.