In the East River Subdistrict, all accessory off-street parking spaces may be provided within parking facilities on zoning lots other than the same zoning lot as the uses to which they are accessory, provided such parking facilities are located within the Special Southern Hunters Point District, and the number of parking spaces within such facility shall not exceed the combined maximum number of spaces permitted on each off-site zoning lot using such facility, less the number of any spaces provided on such zoning lots.