In my experience, our SA gravel roads are generally too rough for standard setup 700c tires and rigid forks (especially around JHB / Magalies.
I found although a gravel setup is generally quicker, regular corrugations and road-wash becomes too tiring - for anything over 4 hours out....
I think the answer is possibly a lightweight hardtail, aero bars, narrower tires around 2.5' and a light fork = less rider fatigue?
My 2c