We are doing the same thing in Ochsenfurt Stellplatz, we did drive to Kitzingen for lunch yesterday, but there was definitely no room at the inn. We tried both campsites and Stellplatz, not wanting to drive far we returned here where I suspect there will always be space as there are no services, I’ve certainly stopped in less attractive locations.They are still here as we are! We have decided to spend a further day here and already some vans have had to turn away as the place is rammed. Neat little town too.
Keep Safe.