We live in Michigan where the winter are coooollld. I always use compressed air to blow out the lines, have a bypass on the hot water heater, and use a valve and hose on the intake side of the water pump to suck what we call "pink lemonade" into the plumbing system for winterization before storage in the fall.
Yes the pink antifreeze fills virtually every inch of plumbing. I know that it would only take a couple of gallons of pink stuff to fill the system and P-traps, but I usually use a lot more than that. I also pour a good amount into the grey and black tanks.
I do not add it to the clear tank anymore. One year I did that and it almost took "forever" to clear it out.
In the spring, it takes a fair amount of flushing to get it all out, but I would rather go the extra mile to winterize and flush than have to deal with cracked lines.
Bob & Nancy
2005 ASLYG 30 SO
2009 Wrangler Toad