Do I have to be worried about the water system in the trailer freezing at high elevation in Rockies in June-July?

Unless there is some kind of funky storm, you should not have any problems. It may get below freezing at night, but it will not stay cold long enough to freeze the water completely. I would worry more about making sure I have the right clothes for all situations and keeping my campsite clean so I don't get any visitors of the large 4 legged variety.



Enjoy!

If concerned, leave the cabinet doors open where you have pipes, like under sinks, and leave your furnace on. If it gets cold enough to freeze pipes (I'd say somewhere around 10 degrees F for more than 6 hrs), it is probably time to move to a warmer, sunnier spot, like Arizona