The dealership will have records.
If they are not going to be helpful 2 or 3 squad cars blocking the entrance and exits to their parking lot will drive their business to zero for as long as they stay. The cops can make them be helpful if they have the will.
My ex, who is in the business in California, pointed out that the perps could have simply stolen the plate and surround off another car.
Regardless, I’d try your special parking technique...
Perps didn’t just buy a car, they pulled the plates off and replaced them with cardboard because they were planning this and didn’t want to get tracked down.