Well, I'm back. Things did not go as planned, but it all worked out.

Just off highway 16 WV.
First observation: maps are important, really. Particularly if you follow a suggestion to check out the (7mi) rail-to-trail in and around Oak Hill. I ended up lost; 11mi detour (+ the 7mi). Note that my, and possibly your, data plan will not work everywhere.
Rather than what I originally intended I decided to go down to Thurmond then head upstream on what google had indicated was a bikable road. The road was rough. Around Thayer I was feeling lost; I asked a man fixing a house: "People don't seem to use it much, for some reason, but t's a good road. Well, it's good for a truck; probably wouldn't want to take a car up there though. You should be OK on a bike." I believed him.
Anyway, I ended up developing an appreciation for MTB. Also why you might want to have one of those bikes with the big tires and a suspension, disc brakes. Large rocks, puddles and deep mud require different technique from pavement. But I got into it.