Forget this internet shit Your Dad and/or Yourself put on some suits, grab a bunch of business cards and visit every real estate agent within 10km or more. They have a massive targeted audience who are constantly moving into rental or purchased properties. They'll love the fact you're the owners and providing a needed service to their clients.
Get the name of the person you're giving the cards to and when you get new business from those cards send the real estate agent a bottle of wine. You'll only need to do this once for each agent and you'll have so much business you'll need to buy a second warehouse Get out there and work it !
Also, have you set up a google places listing for the business ?
You think that would work? How would I approach them? Just ask them nicely and give them business cards?
Yes of course I think that would work but just don't hand a card out. Ask for the sales manager and give a brief description of your business focusing on the benefits for the real estate agent and their customers. Write down some benefit for the real estate agents - a clean a fast move allowing them to rent out the premises quickly, temporary storage for your most valued tenants etc etc.
How has the business progressed since you originally posted ?