BikerBoy from Maryville, IL on 5/14/2020 7:34:16 AM:
You can start at Machens if you want. You will just need to have someone drop you off (there has never been any parking at Machens). A half-mile after you start, you will encounter a large washed out area. Easy for you to hike through (about 50 ft). A little tougher for cyclists.
If you want to park, then Black Walnut is the first place on the Eastern end. But like others said, St. Charles is the best place to park if you want your car to be safer.