I have only used antifreeze in the lines one winter, and I don't plan on ever bothering again. Other than that year, I have just blown the water out. In my 34', after draining the freshwater tank and both holding tanks, and blowing out ALL of the water (let the air flow for a couple of minutes AFTER you see the last water droplets come out of all of the faucets including the shower...) I also just open my pump's pre-filter and drain it as well as removing the fittings to the pump just to make sure it's drained. The pump and pre-filter are probably the most difficult things to do, and they only take a couple of minutes.
I do pour RV antifreeze into the drain P-traps. Once the freshwater tank is drained, I'm not particularly concerned about whether or not there's a little left in the tank. I've never had any problems with it. I generally remove my batteries too, and store them in the basement as they're kind of expensive to let die 'cause I was too lazy to pull 'em out.
AIR 2053 Current: 2006 Born Free 32 RQ Kodiak Chassis, & 1995 Coachmen B-van
Former Airstreams: 1953 Flying Cloud, 1957 Overlander, 1961 Bambi, 1970 Safari Special, 1978 Argosy Minuet, 1985 325 Moho, 1994 Limited 34' Two-door, 1994 B190 "B-Van"