Perhaps some local businesses in that area would allow for their signs (if they have changeable letters) to put up the missing information? Put the pressure on perhaps? Our local businesses will change their signs to root for a high school team or a special event?You would need permission for both I’m sure. Publicize that you’re looking for volunteer homeowners to keep signs in their yard near their mailbox. Some businesses have a grassy area in their parking lots. Maybe they’d give you permission to put some along the front entry landscaping.