Excellent post!
I did the OTET between October/November of '20. I enjoyed your pictures.
I will partially agree with you on the Battelle Darby Creek park "gravel trail". However, I will caution you that Alkire Rd through there is a pretty bad road to ride on. People fly through there and with the combination of the dip through the valley and the turns visibility isn't good. Thats a bad mix for cyclists. You can zoom in on the heat map on Strava and will see that it is a common road route for cyclists. Just be careful and aware of traffic if you choose to do the road. Traffic patterns through the day change, also. Morning is best - but if it is in the middle of your riding day it is what it is.
I have not rode the section through Franklin County (where Columbus is) as I detour between the "trail" and home, so some of that is new. I have some ideas to go back and fill in the gap there.
You found the water fridge. Did you catch the sign on the trail for it? I passed the sign and thought about it, then turned around and checked it out.
Do you know where the cyclist rest stop is on the road section between Fredericksburg/Dalton? What road intersection? I do not recall seeing it, however I did ride in to Apple Creek. When I went through there were some detours with bridges out. There are many ways to slice that cake of road. I hit the laundromat in Apple Creek then kept going and found a spot trail-side E of Dalton to park for the night.
That day was a long ride - and you are correct. Those hills are crazy. It is a demoralizing road section with hill after hill. Miles traveled in a day is only 1/2 of the equation. You have to consider elevation and that segment of the "trail" really brings that theory to light.
My Strava history shows that segment as 26mi that day and 1138ft elevation gain.
At some point I'd like to bridge the OTET to the GAP diverting off the OTET S/SE out of Massilon.