>> VV : a .... don't remind why it's named like this .....

Mr Google seems to think it's purely a Limesurvey thing (all pages with 'vv survey' refer to Limesurvey). Must be lost in the mists of time...

Generating dummy tokens was my first approach, but that would require dummy addresses, names, etc

Nothing that a quick formula in Excel can't solve. Or a function in LS:
www.limesurvey.org/manual/Survey_participants#Dummy_Tokens

You don't need names/adress/email or anything else in token. You need the columpn but can be empty

Denis, there is even a function to create dummy tokens in LS. So not sure about the manual part.