RV Antifreeze is cheap.  One winter, I actually winterized three times.  Once winterized, I usually keep the water heater bypassed until spring unless we're going for a week-long trip somewhere.

If you don't have a hose on the intake side of your pump that you can drop directly into an Antifreeze jug, you really need to look into adding one.  You can either disconnect the intake and replace it with your winterizing hose, or put a Tee and cutoff on the intake side so it's permanently mounted in.  It makes winterizing your camper extremely simple and it can be done in less than 15 minutes as you're departing a campsite or once you're home.  If you're not sure what I'm talking about, I can take a pic of the one in my TT.

I also read of someone recently that either made or got a kit which would manually pump it through the city inlet.

My son is reading over my shoulder and wants me to add the following: :ranger: