The person with the potential problem should review the facts and options with an attorney.
The owners of the mobile lot may very well be charged with unlawful discrimination based on race or national origin.
The website for the WA Human Rights Commission is: http://www.hum.wa.gov/index.htm .
The website for the federal office that enforce federal fair housing laws is: http://www.hud.gov/offices/fheo/index.cfm .
Title VIII of the Civil Rights Act of 1968 (Fair Housing Act), as amended, prohibits discrimination in the sale, rental, and financing of dwellings, and in other housing-related transactions, based on race, color, national origin, religion, sex, familial status (including children under the age of 18 living with parents of legal custodians, pregnant women, and people securing custody of children under the age of 18), and handicap (disability).
Besides the above bases, the WA Law against Discrimination includes sexual orientation.