351.21 PARKING TRAILERS ON RESIDENTIAL LOTS RESTRICTED. 
   No person shall park or occupy any trailer on any lot in a residential district which is situated outside of an approved trailer camp. The parking of only one unoccupied trailer in an accessory private garage building, or in a rear yard, is permitted provided no living quarters are maintained or any business practiced in the trailer while such trailer is so parked or stored. The provisions of this section shall not apply during an emergency when permission is granted by the Building Inspector. (1967 Code §152.06)