Joanne, not sure about that road you asking about.
I hope someone can help you with that information.
I do know that Warner beach is my home town and a little piece of heaven on earth.
Joanne, I had a look at your proposed route via Google Earth and it looks like a fun option.
Unfortuately, the Google Earth team have not driven and provided photography of this road so I cant work out its condition or if you you will need to pay an access fee into Phinda.
If you chose this route, please pass on your findings :)
Joanne, did you brave the D448?