Princess 8, 7 mile beach is about a 15 minute cab ride, too far to walk. Margaritaville is real close to where the tenders dock. You'd probably have time to fit everything in, but don't forget to leave enough to get back on board. I'm not sure what time the Victory arrives or departs, but if you have 8 hours in port you should have enough time. Or....you could book another cruise to visit 7 mile beach
