We have a 2016 Evo by Forest River T2050 travel trailer with the "Arctic Package." That package includes an insulated and enclosed underbelly, increased insulation all the way around, and tank heater pads. The water lines to each appliance and fixture run around the inside of the trailer rather than between the walls, with the exception of the hot and cold lines leading from the water heater to the kitchen sink, which is on a pedestal. However, that one runs just below the thin floor and above the tanks and underbelly insulation, so I'm not terribly concerned about that one freezing, either, as long as we maintain a reasonable temperature inside the rig. We intend to do some winter camping this season at several different ski resorts. Unfortunately, Forest River didn't see protecting the dump valves as anything important when putting together their "Arctic Package." The pipes to the dump valves drop out of the insulated underbelly before terminating at the valves, leaving them rather exposed to the elements and prone to freezing up. As that's got the potential for a messy disaster in cold weather, we decided to do something about it. We've frost-proofed our dump valves and exterior plumbing, and made a video as we completed the job to share our idea: I welcome your feedback, including any weaknesses you still see, or any better ideas around this subject.