This is one of the toughest, but most rewarding sections, in my opinion. There doesn't appear to be any campsites until Morvah, which is close to Pendeen.
You could consider walking to Zennor, or beyond, then diverting inland to the coast road where you could catch a bus back to St Ives and stay there for the evening (or stay at the campsite at Morvah, using the same bus service). The following morning, return to where you finished the previous day using the same bus service, and carry on. The section between Pendeen Watch and Sennen Cove is less challenging, and at only 9 miles you could probably reach Sennen the same day.