That is the very route we use in the Hogsbreath-Keys 100 Race every April.
Great sail, deep water, no reefs to worry about and you will probably have easterly winds around 15 knots (normal) pushing you all the way.
I believe some of the racers have made it in under 2 hours.
You can probably launch at Sombrero Beach (on the east end.., but need to get permission) and pull out at Smathers Beach. I know that Sombrero Beach has gone through some changes, so it might not be available anymore.
If not, you can probably launch at Buccaneer Lodge. after you pull in the parking lot, there is a little dirt road to the left that goes down to a launching ramp. It is on the Bay Side, but an easy sail through the 7-Mile Bridge to the Ocean Side.
Have fun,
Rick