In Bar Harbor at low tide the bar is exposed and good spot. You'd ahve to drop the kayak and go park though. You can come in or go out from the tiny beach at the pier in Bar Harbor in front of the Bar Harbor Inn. Youn cant at Sand beach. THere are also good spots around the island.
Seal beach is good too.
Probably some where along Sewall and the harbors on that side of the island. Good luck and have a great trip. Check weather and tides carefully.