Can the park manager force rules on som e residents and not on others?

No. The MRL provides that the park rule and regulations have to be “reasonable.” (Civil Code 798.45(d)) “Reasonable” often may be subject to court interpretation, but normally rules have to have some rational basis in fact under the circumstances, as well as apply evenly to everyone riding in the park. Park owners and their employees are required to abide by park rules to the same extent as residents have to, except rules regarding age limits or acts of the park owner or park employee undertaken to fulfill park maintenance, management, or operational responsibilities (making noise by pounding nails, use of trucks for maintenance purposes, etc.). (Civil Code 709.23)