A trailer or trailers may be allowed upon a premises as a sales and/or construction office when said trailer is part of the equipment of any person, persons, corporation or partnership that is in the business of constructing residential and nonresidential buildings, provided that the use of the trailer meets the requirements of this chapter, and that said trailer is not used for storing construction materials, and that prior subdivision or site plan approval has been obtained for the development. Where a sales trailer is proposed, site plan or subdivision approval shall identify the location of said trailer and the location and surface materials of parking areas and pedestrian ways in order to provide effective and safe access not only for the public but for emergency service vehicles as well. In no event will any trailer, used under the terms of this subsection, remain on said premises for more than two years from the date of issuance of a construction permit, or past the issuance of a certificate of occupancy for the last residential or nonresidential unit, whichever shall occur first.