I use potable (rv) antifreeze on our camper and toy hauler.
Do not get it in your fresh tank or hot water tank.
After running it through the lines (as in the excellent photo post above) I open the low point drains and catch the amount that will drain and put it down the sink, shower and toilet drains. I like to have a gallon or so in each of the tanks - maybe helps the drain valves from drying and sticking.
To un-winterize ( de-winterize?) - you need to flush each and every line and fixture, including the low point drains. If you start running water past a dead end line that has anti-freeze residue in it like an outside shower or low point drain that is T'd off the main line, the fresh water will keep picking up a bit of antifreeze for days. I try to do the flushing and sanitizing operation at the same time.