The easiest thing to do is T all your systems. Take a five gallon bucket and put a tap with valve in the side on the bottom. Close all the thru hulls and supply all from the bucket valve.
For HVAC put hose from bucket valve to T before HVAC water pump. Pour in 1 gallon pink antifreeze. Turn on the bucket valve, turn on HVAC and have someone outside look for pink discharge, then turn off. All done in about 5 minutes.
Engine and Generator do the same thing and look for pink water from exhaust or 2 gallons, whichever is first for each.
Water system - empty lines with pump pump is 2.8GPM, SO TAKES 28 minutes if system full before you start pumping. I tried bypassing and couldn't get those whale fittings off of Hot water heater, so I just pour pink antifreeze into water system at deck fitting. I use 6 gallons and pump until pink flowing out of all fittings including cockpit shower.
Head, Connect into T, pump until bowl is pink.
Empty waste tank at pump out prior to winterizing head, then after dealing with head, pour 1 gallon down waste deck fitting.
Takes 12 gallons to do entire 356 including the HWH. Would be about 6 if I could bypass the HWH.
Good luck with the whale fittings. I figured it would cost more when I couldn't reattach them next spring than the extra 6 gallons of anti-freeze.