You only need to winterize if you anticipate any freezing of your water lines. If they're inside your popup, they should be fine while you're camping. If they run beneath the trailer, I'd be concerned. In this case, if you really need to use the water, I would pack a blow-out plug and an air compressor just in case the temperature decides to take a nosedive. Here's a link which includes what temps can be like throughout the year.
http://www.emnrd.state.nm.us/EMNRD/p...s/Brantley.htm