My driveway sounds identical to your friends. Actually, mine probably has less elevation change, but it's still pretty significant.
I've plowed 18" of wet snow with a 30-year-old garden tractor without much issue. Chains were necessary on the turf tires. One problem that I ran into was that where my driveway goes from flat to starting its upslope, the angle was too great for the plow that I was using lifted as maximum height. I had to back up through the unplowed snow while dragging the blade, but even doing this, it got through.
Here's are some pictures of what I was using.
Wheel Horse D-180 Events This tractor is leaving my possession on Friday

, and I'm still waiting for my first post-Kubota snowfall. EAGERLY