Max Customers Per Building?

Is it possible to get more than 50 customers for one "house" without editing the buildings.txt or any other game file? I have max advertising on the East Castle, but am only getting 50 customers a day even though I know the 22 girls I stationed there can handle more than 50. (Adding the most customers each girl is able to service per day individually easily gives me upwards of 300.) I'm trying to speed run the Difficult difficulty in as few days as possible, but 7.5 million is a lot of money when I can only make so much each day.