I wonder if there is a way to adopt something analogous to a franchise model here. It strikes me that only the communities that are really, really engaged are going to be able to pull this off (which is true of most public works projects). That being said, it would be great to not have every small town and borough have to figure everything out for themselves. A franchise operator for a fast food restaurant doesn't have to worry about where to buy burgers, the brand of deep fryers, or even the optimal amount of time to fry the tater tots. If there was a full on recipe for doing this that is proven to work, a small number of citizens might be able to make it happen even in places where the local government is ambivalent. A proper setup would include some national branding to help with PR (I.e. Every article in every newspaper about community broadband would use the same name for it). It would include marketing materials for the public as well as briefing packs for local officials, legal briefs for attorneys, etc... On the technical side it would recommend specific hardware, suppliers, and designs.
The advantage to such an approach would be to harness economy of scale at a national level, but allow local communities to drive the process and own the network.
I'm not sure how you would structure it to avoid creating another monopoly in the parent company of the franchises. But perhaps a nonprofit or a corporation 100% owned by the community franchisees would work.