Please use this thread on HOA topics.  As the neighborhood was designed to have an HOA, whenever it is completed it still could.  The current Covenants are very general and will need 'Amendments' to match the residents wishes.

Would a "No Thru Traffic" sign really make a difference?

Yes, a petition written with all the residents signatures to City of Winder Roads and Bridges department can accomplish this.  However to enforce a "No Thru Traffic" will require the participation of the Winder Police Department, via the Neighborhood Watch Program.