The ability to glide to safety is critical, and that means height.
A VP prop is a big help here, if you pull the blue knob all the way out a 182 will glide a LOT farther than a 172. Be prepared, know the correct speed and settings for best glide range and be prepared to waste some time climbing over land to make sure that you will have enough height and some to spare by the time you get to the halfway point.
If the distance over water is longer hire a proper immersion suit and dinghy and get properly traind to use them. Always carry a good quality rescue beacon and get your mayday call in ASAP while you have the height to be in radio range of help.