The problem with the area is that there are relatively few low traffic paved roads.
Au contraire, there's a goodly number of decent roads with little traffic in the area. The problem areas are getting up and down the ridges, of which there are a few.
I'd suggest a few changes. Your route from Sewanee to South Pittsburg has a detour to Kimball that's not much fun; I'd suggest going straight over the Tennessee River there and riding into the Chattanooga suburbs (Wauhatchee / Tiftonia). Alternatively, go north to Tracy City and down to Jasper, then cross the "new blue bridge" on U.S. 41 that opened late last year. Either way, I'd suggest taking TN 134 from Haletown to Wildwood, GA, then north on U.S. 11. 41 from the river bridge to Chattanooga is sorta OK, and while 134 has a lot of interstate traffic noise from I-24, the traffic on 134 is minimal. Lots of motels and some restaurants around Tiftonia, if you don't want to go into downtown Chattanooga. You'll pick 41 up around Moccasin Bend going into Chattanooga.
Leaving Chattanooga, I'd strongly suggest backtracking on 11/41 to TN 58, then stay straight on St. Elmo Ave. until it turns into GA 193. Bear right to go through Flintstone (the bypass gets all the traffic). I'd take GA 341 off to the left and follow it until it runs back into 193 going into Lafayette, again to minimize the traffic, although it has a few more hills.
I'd try to stay on the west side of Rome until you get south of U.S. 411. U.S. 27 is a racetrack with stoplights from downtown until you get beyond everyone's favorite I-75 access road. I'm always amazed when I drive through there how many cars it has, since you just don't see the traffic north, south, or west of town.
I can't tell from your route, but I presume you'll pick up the Silver Comet trail in Rockmart?