If you are getting wash out around that corner it will be hard to control. I imagine during rain you are going to get lots of water coming down the path as well as coming down the hill side. Keeping it against the hillside and sloping things into the hill will help, you will need a shallow ditch on the hillside, but you are going to want a really solid rock base to prevent washout. Ideally you would have a drainage grates, that would take water out and across to dump it away from the road, but that is going to require some extra work and a fair amount material too.This isn't the best, but may give you an idea.
This is a very old video and a lot has changed.The Path is the same though. At the 1:27 mark is the most troubled spot. Once you get past the really really steep 30-40' part, its just steep from there.
https://www.youtube.com/watch?v=eVFEnVTkN8M&feature=youtu.be
