Isn't there a bus between Epcot and the Studios? True, the boat operates from the International Gateway to the Studios, but that would leave no way (by Disney transportation) to get from the front of Epcot to Hollywood Studios without walking all the way through the park.
Since Coral Reef is much closer to Epcot's main entrance than it is the International Gateway, I'd suggest taking the bus from the Studios to Epcot. This should be much faster than boat or walking.