Grumman, what does the local gunsmith shoot into? Mine has a typical steel containment box he fires handguns and rifles into, don't know what kind of hoops he had to jump through to get it approved by the city, maybe having an FFL precludes a local permit.
Sounds like you need to go to a city council meeting and make a motion to consider your proposal. Perhaps you could have a lawyer compose an ordinance which included provisions for inspection and permitting of private testing facilities such as the one you propose. I'm not sure what regulatory arm would be in charge of inspection and permits, perhaps the enviromental health department or just the local PD. Nobody will commit because there is probably no precedent or code currently in existence, so naturally the deer stare blankly at the headlights and hope you will go away.
Just a thought.
Gear