I am sorry I didn't see this post before now. That route is pretty much the one the NA/Melungeons took. It also sounds like we could be connected.

I have never seen the name Surrel before. I have only got back as far as Stanton Nichols born around 1810 in VA. He is on the Morgan County KY census as Stanton Nickell. He married Nancy Gibson born about 1815 in VA. In Ohio on the 1870 census of Highland County he is State Nichols ad he is also on the 1870 census in Clinton County Ohio. But he is listed as Stale Nichols in Clinton CO. I guess because people can't see that the second t is supposed to be crossed.
There is a Shepard connection to my Gibson/Gipson family.

I will be checking out your Surrel Nichols now. If I find anything I will get back with you.