If you're going to start the TAT up in Tennessee here's some local beta (though you've probably already got this covered):
Damn near every town east of Nashville has a Honda dealer because rednecks like four wheelers.
Most of the TAT pictures that I've seen from the TN section you could ride on road race tires. The parts I've ridden, up around Crossville, were all gravel. Nothing to difficult. You may not need your knobbies up in Rocky Top.
If you need any help, hit up Francois over at DualSportTouring. He's a good guy, has stuff you might need, he's local, and he's ridden the TAT best I can remember.
When you get north of Crossville you'll be in Catoosa Wildlife Management Area. There's a fire tower you can climb if you're interested in a short hike; you have to leave your bike at a gate. I can give you directions if you want.
I still have family up in Crossville, TN. If you need help PM me and I'll see if I can find anyone. (Dad's retired and hates cell phones sometimes.)