Do your planning, know your numbers find your best glide speed and rate of descent at that speed. All should be in the poh and be practised !
Let’s assume for illustration 60knots and 500 feet per minute.
so if engine cuts you have a glider
if you are at 10,000 feet as you mention that gives you 20 minutes before your feet are wet (10,000/500). It will be less than that due to prop drag but for illustration I’ll leave it at 20
in 20 minutes at 60 knots you’ll travel 20 nautical miles. (Airspeed not groundspeed, I’ll let you do the headwind/tailwind calculations) As the crossing is - your number - 28 (statute/nautical ?)miles the furthest you are from land is 14 miles.
All of which concludes that the risk of getting wet as a result of engine failure is mathematically non existent at 10,000 feet
still leaves in flight fire, structural problems causing ‘immediate’ descent etc as risks
Personally I wouldn’t bother going as high as 10,000 feet, work the algebra backwards and you can calculate your personal minimum safe height, and how many miles in the middle you are exposed at.
In my view the biggest danger is haze and being unable to distinguish sea from sky. An older and wiser pilot than me took to one side just after my ppl and recommended not to do a channel hop until after getting an IRR.
I followed that advice, understood why on the first time I did it and pass it on whenever I can !
Safe flight