A lot of good responses, some may be over thinking it, but for many it's there baby, so I get it. I buy non-toxic antifreeze at ACE hardware on sale now, buy 5 gallons for each engine and 3 gallons for gen. The fresh water side I just pour in 7 gallons into tank and run through each faucet hot and cold, shower etc. Pour non toxic antifreeze down shower drain and listen for pump to cycle a few times. Lastly I have a tee fitting and a valve for AC, attach a hose with a funnel and pour a 1/2 to 3/4 gal anti freeze until red comes out side. Disconnect batteries, and open all doors and inside hatches, little pat on the transom and go home and have a beer in front of the fire. Yes I use more antifreeze then other approaches, but I get it cheap and I disconnect nothing. Also winters are rather dry compare to Florida so unless you are leaving wrapped until June, I wouldn't be concerned as I never had a problem in over 25 year.