Ah, in that case then your solution does seem to be a good fit. Their nature as a new business makes any review especially damning for future conduct.

However, you wish to slowly increase the number of negative reviews (and that may very well work) but I suspect they will be suspicious given enough time (not an issue if that is your intention, however). If you find your strategy becoming ineffective then do consider a more aggressive stance.

And should you take that route, it may be worth looking into creating background issues between entities taking on the targets identity - for example the individual in question leaves a public review on another business in proximity creating future conflict and animosity between individuals. This could start an indirect chain of actions to occur, more so if you don't simply leave reviews but other methods of communications as well.

Or more simply, call for a variety services to appear at the buildings location at inopportune moments then let the individual deal with the explanations.

And that's only if you find it acceptable using external parties to your benefit. As you stated, due to the nature of this conflict any direct action would unwise - and you being a singular individual means whatever plan you devise will involve lots of pulling strings. Any platform in which they operate should be considered.

Anyhow, let your plans be solid- good luck