Daniel...
About three years ago, my family and I were headed home in our motorhome on I-8. While climbing a mountain pass east of San Diego, I noticed the temperature dropping quickly - faster than normal because a cold front was passing through. It was drizzling, not snowing, and when the moisture hit my windshield it started to freeze near the edges and around the windshield wipers. As we crested a hill and started down a 6% grade (at about 50 mph), I saw at least 10 vehicles spun out and stopped at different angles, all over the freeway in front of us.
People were outside their vehicles and running all over the place. As soon as I touched my brakes to begin slowing, I heard the tires begin to slide on the iced-over road, and the coach started to slip sideways, and spin ever so slightly, nose-left. The ONLY thing I could do was get off the brakes (I had barely applied them), and carefully weave between the people and cars. Luckily, we made it.
But I'm here to tell you that THAT was scary. Cyndi and I later learned that two people died in one of those spinouts when their 4WD SUV skidded off the side of the freeway and down a cliff. My brakes are anti-lock brakes and were/are in good shape, but they had virtually no ability to slow, much less stop my coach in those conditions.
I guess what I'm saying is, if you're going to be pushing a coach in similar conditions, just take it easy and give yourself lots of extra space and time. I know I have no desire to drive my RV through a mountain pass in those conditions again.
Kev