Thanks for thinking of me.
Since I am Canadian and in the province of Québec, I have a question about what you mean by “all temperatures”. What is the coldest temperature you get on a regular basis and what is the worst usual cold temperature?
The AWD GT-Line I tested and made the video about was excellent in the summer and gave me about 450km (280ish miles) of highway range, loaded with stuff and 3 people, at about 71mph. Depending on the winter tire model you buy, the temperature outside, the battery preconditioned or not, the amount of snow on the road, wind, etc, etc, etc. I would guess that you should not have issues with 174 miles. This is an educated guess as I have not tested the EV9 in the winter.
When you say “Along the route from my vacation home in Northern Minnesota to my permanent address the distance to the nearest compatible charging station is 174 miles.” are you 100% sure there are no other DC Fast chargers on the route, from any network? Have you verified the route in both PlugShare and A Better Route Planner?
As for battery degradation, I would not worry about that at all. Kia has an excellent battery management system and enough of a buffer at the top of the range for degradation to take place outside of the useable portion of the battery. My Niro EV had 58,000km in 3 years and the battery had 100% state of health when I sold it, and my EV6 has 84,000km in 3 years and the battery still has 100% state of health.