The most common technique up here (Alaska) is to just not shovel the snow out of the back! I saw an old Datsun P'up truck in Dutch Harbor with a 1000-pound chunk concrete in the back. But that may have been more about the winds (I've experienced gusts to 127 mph there).
150 pounds isn't a lot compared to a 4,000-pound (or more) truck. I'd be thinking 500 pounds or so. Make it stuff you can use in a pinch (but not valuable, stealable stuff) like sandbags, some 2x8 planks (under the sandbags), some tow chains (hidden under the planks and sandbags).
In some snow and wind conditions, the weight really helps. As do better tires.
On ice, great tires help much more than weight. Driving slowly and staying home during the worst of it helps even more.
Something that California skiiers are better at than most anyone is using tire chains. They're a pain, but make any vehicle as capable as it can be for winter travel. For a winter Midwest or East Coast roadtrip, I'll bring one or sets in my luggage which always gets TSA's attention (especially that time I had a set in my carry-on, but they let me through).