" All of the above are best out of school holidays and the road through the park and to Maputo can get very very interesting during and after heavy rains. Most would say that doing it as a single vehicle is not an option but you have a Patrol so WTF"
Yeah.... that road can be quite a load of fun... good and bad. I have traveled this road about 6 times over the years by ourselves, and either ( from Ponta du Oura ) taken the road to the right to catch the rusty but great experience ferry across the Maputo harbour mouth, or to the left up towards Matola and out at Komatipoort. If you have patience and are willing to risk some serious pot holes, then it is a great drive, especially if you go catch the ferry into Maputo town.
The road to the left that takes you up to Matola has a detour ( it may be finished now.... not sure ) where an old bridge was either destroyed or broken up to make way for a new bridge made us have to back track to find another route around, but with a good GPS system, there should be no problem.
Ideally travelling in 2 vehicles would be the best bet for sure.
Nissan Patrol GL 4.2 Diesel Turbo (Iron Maiden)
Nissan SANI 3.0 V6 4x4 (SOLD)
Isuzu KB 280 DT 2x4 ('ol Smokey) - SOLD
Suzuki TL 1000R "V twin" (Growler) - SOLD