The next day after filling up with cheap diesel in Luxembourg we stayed at a marina on the Mosel. It has a restaurant attached and we all had a pizza except for one of the party that in a moment of madness got a salad. There used to be a large campsite nextdoor which has now closed.
We stayed at https://www.schengen.lu/port-de-schwebsingen/
Price was €14.
Free aire a few hundred yards further along river.