Hey Zip,
One time I started at the turnout on hwy 38 right before Morton Peak road. The turnout sort of overlooks the bed of Mill Creek.
I crossed Mill Creek to a small tributary creek with a good sized waterfall. I don't know what that waterfall is called (me and my friends named it Alby Falls). To the left of the falls we climbed some old roots to the top of the falls. We followed that small creek pretty far back. Eventually it should meet up with the Yucaipa Ridge truck trail. We never got there though. We had to turn back because, of all things, there was a good sized mud slide. One of our party got stuck in the mud and lost his hiking boot.
We ended up turning around. It looked doable. I'm not sure how steep it gets past there.
If I get a moment I'll try getting a map link for where we started. But basically, it's that first turnout on the right as you're heading up 38.
