That is so cool you like going out and searching for old rail roads.I to love searching out old and forgotten railways. I love the old logging and mining railroads just like what you have above. I have researched the rail roads around northern california, they are very immpersive. You should check out some of the old logging railroads from the redwood area. Send me a pm and we can discuss some places to go.
The Redwoods would be an awesome place to explore old forgotten railroads. In the fall would be a good time, alot less people to deal with. I will get back to you. I have a backpacking trip coming up in september, so maybe after.
Yes after september would be great. If you realy know where to look you can find some pretty cool stuff. In the sierras there is a rich railroading history. Lots of cool stuff out there. You would love it.