[Fulltiming]

I agree that it is preferable to drain the water heater and keep the antifreeze out of it. It can be difficult to get all the antifreeze out of the water heater again and with a bypass and drained, you will not have any issues. I used that technique in my RV's pre-Newell. The Newell I have kept plugged in and kept the wet bay warm with heaters so I have not had to ever use antifreeze in it.

Although use of RV antifreeze will, in theory, not hurt you, it does mess up the taste of the water until it is ALL flushed out of the system and I have found that the water heater doesn't flush out as well as the rest of the system.