To add to that last statement, in some situations, maybe in "many situations when using an RV" putting insulation around the pipes does more harm than good. Depending on where the pipes are located, putting foam "pipe wrap" on them may actually cause them to freeze and prevent them from thawing. If the foam is put on pipes near the frame rails, then allowed to "lay against the steel rail" the foam can compress, reducing the insulation and allowing the pipe to freeze. As you heat the bottom/belly of the trailer, the foam around the pipe can prevent the heat from reaching the frozen pipe, making it impossible to thaw it for much longer than if the pipe was "open to the warmth"....
I don't know of any Keystone product, from the cheapest entry level to the most expensive "luxury" model that will remain functional in extremely cold weather without using outrageously large amounts of propane, electricity or both. By "outrageously large amounts" I mean that you can easily use as much energy to heat/live in a 30' (240 square foot) RV as you would use in a 1000 square foot "conventional house"....
So, don't believe the "sales hype" (trying to refrain from calling it BS) from the RV brochures and salesmen. While some models are a "bit better in staying warm" no Keystone trailer will remain "functional and cozy warm" in below zero weather without using every BTU of propane, electric heating and often times, also the stovetop burners to keep it above 70.
Now, with additional measures like skirting, insulation on the windows, sealing the slides to prevent air leaks, possibly adding foam sheeting to the outside ends of the slides and to the slide floors you can reduce propane consumption a bit, but plan on a 30 pound tank every 3 or 4 days when it's below freezing and the wind is blowing..... Even then, you won't be casually walking from your "nice warm bed" to the toilet in the middle of the night in your skivvies.....
Oh, and don't forget the three or more "plastic single layer domes" over all the roof vents. They "leak heat" through that plastic dome at the same rate as opening a window or the front door. Use "vent pillows" or foam blocks cut to fit to help reduce the heat loss... Don't forget to remove the bathroom vent pillow and turn on the fan when showering or you'll have "rain on the inside of the windows. Same with boiling water, cooking on the stove. Any excess moisture will collect, first on the windows, next on the cooler wall surfaces, like behind the sofa, against the spot where the mattress touches the wall, etc. So even using "insulation" sometimes you have to adjust using it to prevent even "worse things" from happening.