Hopefully you can get Charter to fall in line. If not, and you need some fundamentals on setting up a co-op WISP, there is an excellent forum on this very sight with some of the best and brightest in the WISP industry. It would probably be a good place to do some lurking and reading.
There might even be someone nearby who you could hire to consult or get you set up.
»Wireless Service Providers
I sold a tiny WISP to a co-op (former customers). It didn't work out for me, profit-wise, but was great for them as a non-profit setup. I was glad to be rid of it, and they were glad to have something besides dialup.--
If someone refers to herself / himself as a "guru", they probably aren't.