X10
I57 down to I24 Paducah,to I65 Nashville, and then what I do is take a turn at Birmingham to Route 20 over to I75 and that down to Florida.
Why you ask do I take this route? It is a 'pleasant' drive in an RV with nice roads. AND to avoid the steep grade in Chattanooga.
Be aware that if you take the Chattanooga route you will encounter a 7-1/2% grade STRAIGHT DOWN. I did it ONCE and NEVER again!. :E
IMHO, JMHO I'd think about it with your new to you 5'er. Bring a change of clothes if you opt to take that route with that grade. :W