"Nice reply, but what then is the point of "winterizing"? The last few years it has become bitterly cold starting in November... if I winterize it then, and then take it out in April, we're talking 5+ months of inactivity. Should I just open the garage and run everything indoors monthly? "
The point of winterizing is to prevent damage occasioned by cold temperatures. Doing so should not prevent you from periodically running the engine and all of the on board systems(your water heater being the exception). I make it a point to check on the coach at least once a month but we usually use it at least that much year round. If you are in covered/enclosed storage just back it out far enough for the exhaust to sufficiently dissipate and fire up the engine, generator, furnace etc.
I must admit that living here in Tucson "winterizing" consists mainly of restocking the bar (:B), but for most folks it is a more proactive process. From late December through February after each trip I drain all of the water lines and add a quart of pink RV antifreeze to the black and grey tanks along with a cup full down the sink drains. We see temps in the mid 30 to 20's on a regular basis and on rare occasions have it drop briefly down into the teens. Since these lows last from about four AM till six so prolonged exposure is rare.
:C