A few additional ideas. . .when you are adding the antifreeze to the engine, make sure that the engine has run for awhile and reached a warm temperature. If you suck the antifreeze into a cold engine, the thermostat will not allow the water to circulate through the engine. Rather, the antifreeze will bypass the engine block.

Make sure the gas tank is completely full. Any space in the tank will allow condensation. The water will make its way into the fuel line come spring and cause a bunch of problems. You might consider a small amount of fuel stabilizer for the tank.

Make sure you close all the through hulls. Put a little antifreeze in the head and any other place where water might still linger such as the sink. Run out the water in the water tank.

Take the batteries home and put them on a chargr periodically. Spray a little mildew cleaner along the cabin liner and take home the cushions.

I am from North Carolina. There are some great frostbite sailing through the winter.