Well, I guess now that they are an incorporated entity you and your club members can take them on at their own game.
Speaking of noise complaints, how many pilots/club members have noise issues with dogs, parties, noisy/nosey neighbours, noisy farm machinery, and other disturbances to their peace and quiet whilst at home? I'm quite sure you could rustle up a few names, and possibly use the existing council bylaws/tenancy laws/and environmental laws with noise logs to approach the anti-airport group.
There is also the issue of "retrograde" claims being made. A facility that has been in use for a substantial time with little to no complaints in years gone by, and with full council approval for that activity to take place under all legislative grounds, suddenly without any significant change in operation becomes a "target" of a new group. Why the sudden interest? WHO IS FUNDING THE "COMPLAINTS" (local "Green" group? Local developers? expanse of land for sale in the near future? Council strapped for cash?). More dirt needs to be dug up here...I'm sure there is something else in the background happening.
Get the local Media up to speed on some of these points and take them out to the airport and nearby surrounds for a visit during a typical day.
Hope these suggestions help...