Here's the answer:
$20 on Amazon.
A hand pump that pushes antifreeze directly into the City Water connection.
If possible blow system out with air first. Makes it easier to remove onboard filter (if equipped) without spilling.
Open low point drains to drain as much water as possible.
Drain water tank and when empty run water pump. Most water in tank to pump line will be exelled through low point drain. Then remove strainer bowl on pump and empty.
Bypass Water heater and drain it.
Close Low point drains and add antifreeze with a faucet as far as possible away from water source. When Antifreeze shows there, go back and open one faucet at a time, pumping until it shows antifreeze. Flush toilet while pumping. Don't forget outside shower and outside kitchen sink if you have one.
You will need a helper. Good news is that you should only need to pump two gallons or so. Removing water first makes sure the antifreeze is full strength and you don't have to pump extra to make sure water is flushed.