Here's a tip for descending safely on roads you don't know with lousy pavement - brake a lot setting up for the turn, and turn in late. You might feel like you are slowing down a lot, but the modified line is safer if you are not sure of the road. This will let you see much more of the turn before you commit to a line, and will give you much more margin of error if you need to change your line. Since you're going downhill, it's easy to accelerate through the turn and get right back up to speed. You'll also start accelerating earlier in the corner than people who turn in early, so you won't lose as much time as you'd think. It's not the fastest way down (people who really know the road will be faster), but it's the fastest safe way down on an unfamiliar, poor quality road.

this was how they taught us to corner on an unfamiliar racetrack when I was in auto racing school (God, was it really 20 years ago) - as you learn the corner you can turn in earlier and earlier on subsequent laps until you start running out of track at the trackout (ie, the end of the corner) - then you know when you've got the corner nailed. Turning in too early is just a recipe for disaster.

JB