There's some very good advice in the above posts. The second year you do it, it will take 15 minutes. The first takes longer because you're worrying about getting everything.
Check your manual for your washer. Ours says to just pour in a cup or so of antifreeze and run the spin and drain cycle for xx seconds. So I did it that way rather than using the water pump. But if your manual doesn't have specifics, Ken's method is a good one. It probably works well even if the manual specifies a method.
Mine takes about two gallons but I always have three available, just in case.
The purpose of pouring some antifreeze in the toilet is to keep the slide seal from drying out. Antifreeze doesn't evaporate. Put it in the toilet bowl, don't flush it out.
One other thing - either remove the battery and store it where it won't freeze, or hook the rig up to shore power if available, or check the battery water level and maybe put it on a trickle charge once per month during the winter. We kept ours hooked up to shore power but we had that option avaialable. Now we just go south instead of winterizing.
