Wow!
I leave every thing on, but close the sea cocks.
The hold n treat goes to "no discharge" mode
Except...
In the winter I leave one of the diesel furnaces on freeze protect mode. Keeps the boat above freezing, and dry inside so no mold come spring. Burns about a hundred gallons of diesel during the 5 month lay up.
I also set two of the 750 watt electric built in heaters to 35 degrees.
and I turn the water pump and vacuflush heads off.
Yes the boat is fully winterized, and yes I hire a boat watch company to check on it weekly, which includes a interior walk through.
I also have a alarm system that alerts me if there is a problem, and several cameras I stare at longingly daily.