I drive a subset of this route pretty frequently, roughly from Rocklin to Truckee, and its pretty good! Autopilot definitely makes the ride more relaxing and easy, but I do usually take manual control (or at least have my hands on the wheel, gently "guiding" autopilot to the right path) during a few areas with a particularly small shoulder and sharp turns. There are some pretty long stretches it can handle without intervention, but you definitely won't quite be able to do the entire route on autopilot with no manual control quite yet, but it's improving really quickly!
Which variant of the model 3 are you planning on getting? Keep in mind the slope has a pretty significant effect on range. As a rule of thumb, the 60 mile stretch I drive most often tends to use 100 miles of range uphill, but going that same 60 miles downhill only uses around 10-20 miles of range, and you'll see your range actually go up for a while on the way!
While the trip certainly can be done on a standard range car, I'd recommend the long range variant if it's within your price range, for a much more stress free commute, and ensuring you won't need to stop at a supercharger on the way back, especially in the winter.
