In all cases where a district boundary divides a lot in one ownership and more than 50% of the area of such lot lies in the less-restricted district, the regulations prescribed by this chapter for the less-restricted district may be extended by the Board of Appeals to such portion of the more restricted portion of said lot which lies within 50 feet of such district boundary. For purposes of this section, the more-restricted district shall be deemed to be that district which is subject to regulations that prohibit the use intended to be made of said lot or that require higher standards with respect to density, coverage, yards, screening, landscaping, parking, loading and similar requirements.