My driveway is similar to yours in length and slope.
It was excavated into the hill in 1972 when the house was built. Today the maximum grade of a legal driveway is 8 degrees.
So, after living there for almost ten years and going through four plow guys I bought a Massey Ferguson 4WD Cab tractor.
Your setup sounds nice, esp. the cab part when the wind's 300 mph :-)
I have an old Deere 318 with a blade and chains so am able to pretty much manage (so far).
Later this year I'll be beating the bushes to find some guy/kids to do it for me while this aging fella watches from the window !