lists a city park and a Cracker Barrel as places that allow overnight parking.
It heavily depends on you're at in the city though. Nashville is a pretty big place. Check Walmarts, Cabelas, truck stops, etc. There's plenty of options in places like that.
Now it would be a different story if you were one of the folks that come on here asking about free parking in downtown LA while they work on their build at the same time