I would have opted to reduce the passenger load and carried some spare fuel down the back in jerry cans.
And would have fallen foul of pretty much any rule in the book. Carriage of dangerous goods, BIG, BIG no-no (even in Africa, trust me, I know)
What I don't quite get here (and I have flown in Africa) is why they didn't do an en-route refueling stop somewhere. There are plenty of airfields between Durban and Beira, certainly enough within RSA, to refuel.
Admittedly, the 100LL situation in Africa can be, shall we say, challenging, but usually a couple of phone calls sort the problem out. At the very least give you enough info to make an informed go/no-go decision. Having to adjust your route/plans for fuel stops is, in my experience, just par for the course.
On a very different note - am I the only one noticing how every accident pilot running out of fuel, flying into mountains, etc, is always described as being
"extremely careful", "would always follow safety and procedure" and was "meticulous".
Not saying it can't/won't ever happen to me, but still.....