We took 127 (one twenty seven)South to Chattanooga then to I-75 to Atlanta, with our 36 ft motor home towing, with no problems. We were heading to Florida. I am not familiar enough to that region to advise a cut-across off of I-75 to save you from going south to go north over to Gainesville. We have been down 27 (twenty seven) and 68, and wouldn't really advise that as it winds around and is pretty steep in some places. Sorry not much help as we have only been south that one trip. (how was Cumberland Mountain State Park? Isn't it pretty-we live just west of the park.)
on edit-if your google is suggesting using Hwy 30 that runs from Pikeville to Dayton (between 127 and 27) I've been through there by car and although it is very pretty, it is mountainous and I wouldn't recommend with motor home.