Living in the Midwest I do the blow-down then add antifreeze to be safe. Our 2019 Globetrotter came with a factory winterizing valve (originally installed backwards).
I’ve never been able to get the pump to pull antifreeze from a gallon bottle. I found using a Hopkins FloTool funnel
with an on-off valve connected to the feed line worked but you had to keep refilling the funnel or get someone to run the faucets while you added antifreeze.
Today I found a solution - turns out the FloTool valve threads are the same as the antifreeze bottle’s. This allows the pump to draw a full gallon at a time. I made a simple stand out of scrap wood to hold the bottle upside down and clamped it to the wardrobe floor. You could make a wire hanger for the bottle but the stand worked for me.
**You need to punch a vent hole in the bottom of the bottle before turning the pump on.**
After the first gallon, just cut a hole in the bottom of the bottle to refill it. Save that bottle for next year.