My 2 cents: If you are renting a car in North Sound, do The Baths by vehicle. Getting in and out by swimming can be daunting and if you go early in the morning or late in the afternoon you will lose the crowds instead of being one of them. You can get to Spring Bay via another cool place called The Crawl. It is on the road to the Baths and is part of the National Parks system. Very cool lagoon formed by the same rock formations as the Baths. Much easier than trying to dinghy in. That leaves you time to do both Deadmans and Cooper.

There is a fresh water pool at the Top of the Baths. You could take a dip there, rinse off and freshen up for Coco Maya. Don't forget to stop at Mad Dog! Cool, funky bar, kid friendly right at the Baths. Good lunch stop.
Have a blast!!!!