Temporary construction trailers and one sign not exceeding 12 square feet, advertising the prime contractor, subcontractor(s), architect, financing institution and similar data for the period of construction, beginning with the issuance of a building permit and concluding with the issuance of a certificate of occupancy or one year, whichever is less, are permitted, provided the trailer and sign are on site where construction is taking place and set back at least 15 feet from all lot lines. If the construction is to take place for a period exceeding one year, the developer may apply for and the Zoning Officer may grant extensions to the time during which the sign may occupy the site. The applicant should apply at least one month before the expiration of the time period.