A commercial coach or recreational vehicle may be used as a temporary office for a period of time not to exceed one hundred twenty (120) days in duration in specific instances where a permanent structure housing an existing licensed business has been destroyed or damaged to the extent that it is rendered unusable. The sitting of temporary structures shall be approved by the Building Official, and shall not require site plan review in compliance with Chapter 19.49. Temporary structures shall maintain a twenty foot (20') separation from property lines and/or other buildings or structures.