Actually, the worst experiences I've seen were in Minot, North Dakota. Think ridiculous windchill. With that said, common sense dictates things need to flow downhill so they don't get water trapped and freeze up.
The guy I worked with in the Minot area (my first apprenticeship, if you could very vaguely think of it as that) actually disagreed with the published procedure for draining all the tanks- he was of the opinion that just allows more moisture in causing more problems. This was even on a 936A2...
I have never been to the Dakota's. I would imagine it would be pretty miserable in the winter with the wind whipping across the open ground. The old cowboy movies show it that way.
I started working at a place that used MV's to construct steel high lines in 1983. I knew a lot about gas engines and pickup trucks but that was about it. In fairly short order, I was given a Duce to overhaul. I saw it as a pickup on steroids and did fairly well. These were WWII and Korean vintage machines. Brakes had a "booster" and we had a few dozen "air over hydraulic" 5 Tons with multi-fuel power plants.
Fell into servicing the lowboy trailers that hauled the trucks and discovered a new animal. The "
whining steering wheel holder". They would always have something to whine about. It started with air leaks. Their tractors would sit for a half hour and have no air... It took time, but eventually I managed to get the pair of Astro95's and a pair of Road Boss, and a half dozen Ford 9000's to the point they would still have air after sitting overnight. Lots of time with spray bottles of dish soap...
ANYHOW, the story about air and water and daily draining came to me from one of the better drivers. Apparently at some point in his lifetime, he had encountered ice in air - so he was hard core about draining. That caused me to start looking at the trailers. They all had tank drains but you had to crawl under the trailer and/or lay on the ground to do it. Over time, I got that made better with pull cables carefully routed so they wouldn't get snagged on anything. Those weren't perfect but they were better than drivers ignoring it because it was a pain... They would use them if it was easy. I was guessing that was how the 9xx series ended up with 4 drains on the passenger step. Easy, it gets done. Pain, it gets ignored.
I learned a lot and eventually earned the respect of the drivers. Especially when I learned how to adjust their trailer brakes! One piece at the time. The "old guy" that taught me how to do that was in his late 30's (haha). He took an interest in me - OR - he had me do the stuff he didn't want to do - not sure which. Slack Adjusters on a tractor or a trailer was no big deal, but on a lowboy it can be pretty tight under there... He didn't like doing it, so that became my job.