The state council shall encourage the adoption of ordinances in each political subdivision in the State which would permit the maintenance and construction of residences for persons with developmental disabilities, including those developmentally disabled persons defined in this chapter and in section 202 of the Federal Housing Act of 1959, as amended. The ordinances should include provisions for permitting an appropriate number of unrelated persons with developmental disabilities and two supervisory staff to reside in a single-family dwelling provided that in determining the appropriate number, the political subdivisions should consider the cost of maintenance and construction of the residence, in order that financial obligations can be met.