Hi Christine -
This is admittedly a tough topic. I have lived on site at different points during my career, and the discounts have been different with each company I have worked for. Some concessions have also been dependent on position held as well as tenure. Some haven't even offered a discount and have discouraged employees from living on site, while I have had other companies offer free rent & utilities.
First, I would like to point out that at 3 times the monthly rent of $1020, your employees are not income qualifying for the homes they are attempting to rent. Even with a discounted rate, (assuming the rent is $1020 less a $200 per month discount for a total of $820/mo) your employees just barely qualify. 3 times is fairly industry standard, so assuming the community is market rate, this could easily be your first talking point.
Having lived on site, it's a tough task that routinely requires an employee to go above and beyond what they already do in a normal day. How often are your employees tasked with something after hours? Is this something you can bring to the attention of corporate? Are they closing the pool, helping residents or related? Are they checking lights after hours? Are they chatting with tenants while on the grounds?
You also have to keep in mind the financial aspect of the management; Would it be more cost effective to give your employees an increased discount in lieu of a raise? Are there other options that can produce the same morale boost without cutting into rental income? Would you consider other options such as asking management to pay utilities - 10% is roughly $100 so that can easily be an electric bill, water bill or similar.
Also, I always liked the tenure option.
For every year worked with a company, an additional percentage is added onto the employee concession. For example: 1 year = 20%, 2 years = 25% and so on.
I hope some of this helps, and remember all you can do sometimes is ask. Best of luck!