In all one-family, two-family, multiple-family and mobile home districts, no open accessory storage or display outside a building containing materials or commodities for sale at wholesale or retail or for storage purposes shall be permitted nor shall any motor vehicle or machinery storage, other than that which is incidental to the use of a premises as herein provided, be permitted; nor shall any truck or commercial vehicle storage be permitted, except that one (1) panel delivery or pickup truck not exceeding one and one-half (1-1/2) ton capacity, may be stored by the owner of a premises when such vehicle storage is incidental to the main use of such premises.