I was chatting with a retired BA captain at a fly-in a few years ago who regularly flies his single on water crossings, I asked him what was his preferred altitude. He said absolutely no more than 300 feet AMSL. His reasoning was that if the engine does quit he did not want to go through the mental trauma of the "who's and why's" or the " woulda shoulda coulda" of his entire life's path as he glides down from up high, he would rather just get straight in the drink and be done with it.
Maybe he was onto something there. Not much point spending your final moments on earth cursing the ex wife and the milkman.