Special use permit. Applicants with prior nonconforming signs may request a special permit from the Planning Board to continue their use upon a change in use, expansion of use or change of tenancy. In considering such requests, the Planning Board shall determine whether continuation of said signs would negatively impact the historic or scenic character of the community. Once granted, any such special use permit will automatically expire if the use, business or business name changes or ceases for more than six months.