We drive northern 1/2 of The Trace twice a year and have driven the complete route 5 or 6 times in our 40' DP towing a Sport Trac. Watch the signs at turn outs, a few are labeled for low overhead and no turn around. Meriweather Lewis Park has free no hookup sites that can fit a big rig. There is one fuel stop only on The Trace about mid way unless it's been closed in the past year. So fuel on the top 1/2 of your tank. Our favorite rest stop is the turn out just north of the Tennessee River, great place for lunch and to watch the river traffic.
There is no access to the new outer most belt around Nashville from the trace, no commercial traffic is allowed on any part of the trace.