Fill a one liter soda bottle--or even a 20 ounce bottle--with WW fluid and keep it in the trunk with the jumper cables and the other auto rescue supplies.

I've been amazed at how much washer fluid I've gone through since moving to CO (get caught in ski traffic on i70 on a bad weekend and you'll probably use a quart). Luckily I have a fairly big fluid tank, and remember to check it often enough. Biggest problem I usually have is the rear wiper will freeze and not make any contact with the glass.

As for carrying a spare wiper, that is one of the nice things about having 3 windshield wipers that are all the same length (FJ cruiser). Something happens to one, you still have 2, which will clear enough of the window to have a good view.