Hi Joost! I found other examples with a restriction to vehicles traffic sign on the entrance to more obvious parkings for features of public interest in the surroundings, 
Here in the recreation area of Kockelscheuer, it's clearly stated "parking" on one of the signs though:
https://maps.app.goo.gl/pkCmyxhSkszBQNT79
OSM: https://www.openstreetmap.org/node/965328073

Or with the Roman Villa of Goeblange. Funny extra, there are even 2 board signs, before entering and after the parking. 
https://maps.app.goo.gl/3kcae5zJyxYaEkBF9 
OSM: https://www.openstreetmap.org/way/424582816
I do remember a discussion with Stereo that this sign was more perceived like "restricted but access is OK to a specific destination". Letting you the resolvation if you think it's OK. 

Have a nice day! 


