Work backwards.
A 3 PM departure means your DME pickup will (most likely) be between noon and 12:15.
They 'suggest' you be there fifteen minutes early. Now it's 11:45 - 12:00.
Allow about fifteen minutes extra if you need to get anything from Bell Services. 11:30 - 11:45
Five minutes to get from the boat dock to the bus stop. 11:25 - 11:40
Ten minutes for the ride. 11:15 - 11:30. Assumes boat is there and ready to depart as you board.
Ten minutes to exit park. 11:05 - 11:20.
If you got seated RIGHT on time, maybe there's a slight chance you can make it. Remember, though, a 10:10 reservation time simply means you get the next available table for your size party at or after that time. If you have any kind of wait, you might be in trouble.