I previously lived in an area where the neighborhood resident's association applied for and received "national historic district" designation. Doing so allowed us to create and enforce design guidelines for both new construction and renovation of existing property. Deed covenants make it clear to new purchasers, prior to purchase, what they will legally be held to.
The system actually works. The neighborhood became desirable, vacant lots were developed, and the new houses that were built look very appropriate to the period, style, and siting of the existing houses. Inappropriate remodeling projects stopped butchering old houses. It's not developer-unfriendly. More than 100 houses have been built in our old area since the NHD designation.
Some NHD neighborhoods have been able to exert considerable clout. Bungalow Heaven, in Pasadena California, has been fighting a freeway construction project that would bisect their neighborhood.
The National Trust for Historic Preservation can help with info on getting NHD status. I think they also sometimes will weigh in to help deal with specific projects.
This info may be a little late for the Oaks at Eden, but maybe it can help. I hope so.