Visited yesterday without charging.
The charger is after the forbidden driving sign, before the gates that lead inside the camping. After the sign there is the check-in zone with parking spots, then you continue and turn right, and the charger is the last spot before the gate.
Based on its location and the driving ban sign, I assume the charger is meant for customers of the camping or restaurant, but nothing is stated on the charger itself. The sign at the entrance of the road has the ban except "Benützer Campingplatz und Bootshafen".
Restaurant guests are usually expected to park in the lot that's at the beginning of the road, before the ban sign.