I think your best bet would be to talk to many of the ops here that DO NOT cater to cruise ship clientele (clients here today, gone tomorrow). The goal for the great majority of these small, independent ops, is to establish long-term relationships with clients who will enjoy their dives so much that they will return over and over again. They have attract some very advanced divers, but they also have plenty of new divers also. Contact a couple of them, explain the situation, and see what they can advise. I dive with Living Underwater and they have a LOT of repeat customers.