If you’re going to do it in a non-turbine single, I think the thought of a Malibu, Mirage or M350 Is the best solution. Plenty of range and the payload is good for an 800 nm flight. Traveling over 200 knots makes the trip length bearable. And if you’re not going to be in a twin or turbine, with single engine concerns. Flying it at 23 to 25,000 feet, it almost always will be within glide of Land or at least warm water close to land. No wind glide at 25,000 feet is going to be 58 nautical miles With a windmilling prop, farther, if you’re lucky enough for the prop to stop. Plus you have radar which comes in handy since there’s no Nexrad or ADBS weather down there.
Sad to say that there’s a ditching record with the PA46, but happy to say that as far as I know the ditching record is perfect. The plane ditches very well given that it’s retractable, has a long, strong, and watertight pressurized fuselage