That 63-foot mast height could be a problem at 7-Mile Bridge, especially on a windy day. Even at low tide it's a tight squeeze for you, and I really wouldn't chance it. Key West is only another 40 miles and there are no bridges over the Northwest Channel. Lots of deep water and both sides of the Northwest Channel are protected with skinny-water flats, which makes for an easy ride--even in a 20-knot wind.
If the weather gets a bit snotty, which it sometimes does around Key West, you'll find plenty of sheltered locations to drop the hook near Tank and Tree islands. Unfortunately, you draw too much water to duck into Mule Key Basin, which is a beautiful place to watch the sunset from the cockpit.