Wilosons Promontory to Devonport is 125 nautical miles with one island, Curtis within gliding distance and another closer to Wilsons Prom. One hour in most SE lighties less about 12 nm glide distance at either end brings it back to 45 minutes out of gliding distance. Average SE engine goes 1500, 1700 or 2000 hrs between overhauls, most have been overhauled twice or three times, never failed or stopped. The odds against the engine failing catastrophically in the occasional 45 minutes out of gliding istance are extremely remote. I have done it hundreds of times over the past 40 years and many people have done it lot more often than me, including the guy who used to fly Bankstown, Mallacoota, Flinders Island carrying crayfish, day or night, any weather. If it was that dangerous CASA would not permit SE flights between Moorabin- Devonport direct, 169 nm over water. Done that often enough too. What is the fuss about. Just do it.