Good luck! I was out there in march. We trolled for 8 hours only to see a few mahi. Trip started great. Water was very calm, then out of nowhere it got ROUGH. Next time I go out there i'm jumping on the Bite ME. They do shared charters.
Do what the locals do go to Walmart on Henry Street in Kona buy a mask fins snorkel and a Hawaiian sling and fish the coast or try these guys http://fishingkonastyle.com/ either way have a great trip Aloha