very simple plan. At the shop we blow, and antifreeze.
Use your existing water hose regulator, screw it in to the city water connection. Screw the blow out plug to the regulator. NOW- open every faucet, every low point drain, and leave the plug out of your water heater- (do NOT) bypass the water heater. Now have one person apply the air to the blow out plug, while some else goes inside and monitors the water from the faucets, and flushes the toilet.
Now you can remove air flow. Remove plug/regulator from city hookup. Leave faucets/water heater/low points open. You are good to go.
I started with nothing, and still have most of it left
2001 Jayco KIWI 23B
2003 Jeep Grand Cherokee 4.7 AWD