Signs. Not more than one sign for each entrance to a public street from a mobile home park or trailer court shall be constructed. In R-4 districts such signs shall not exceed twenty square feet in area or eight feet in height above the ground and must be parallel to the property line. If illuminated, it shall be by indirect lighting. In the H-S district, such sign shall not exceed seventy-five square feet in area or twenty-five feet in height from the ground, nor more than ten feet to the entrance from the public street to the mobile home or trailer park.