Should be valid.
Point of turnaround is the furthest stop from your origin. According to gcmap:
YHZ-CPT 7,471
YHZ-JNB 7,544
YHZ-HDS 7,596
Which means HDS is your destination. You have one stopover in CPT on the way there, and also an open jaw at your destination (HDS-JNB). Should be fine.