I live in Nashville, have driven I65 frequently for many years, and am hard-pressed to think of anything that might fit what you're looking for.
If by "scenic" you mean a downtown view, one place does come to mind that is only a short distance off I65, near the perimeter loop. This, however, would not be something I would recommend while pulling a trailer. It is not "officially" an overlook, but just what I would consider a good view of the city.
I realize that I probably have not been helpful. Let me know if there's any other info that I might be able to share. If we're around, we'd be happy to give you the "nickel tour".