Any accessory use that is clearly customary and incidental to any principal use permitted in this district use shall be permitted on the same or on a contiguous lot, except that the following provisions and limitations shall apply to certain accessory uses:
a.
Above-grade parking decks and garages shall not be permitted in conjunction with a tract containing principal building(s) having a gross floor area less than fifty thousand (50,000) square feet.
b.
Inventory or stock clearance sales may be permitted on lots principally devoted to a wholesale business establishment, light industrial use or other non-retail commercial use, provided no more than four (4) such sales shall be permitted per year.