I've been through this rigmarole at my old RC club. When the field was purchased, there were no houses nearby, and only a recycling plant next door, that made enough noise to wake the dead for company.
That was in 1988.
Fast foward to the 21st century and there are houses dotted all over the place now, and of course, RC models have grown in size, to the point where 70" - 80" 50cc models seem to have replaced the ubiquitous '40' sized models of yore.
It doesn't take a genius to figure out it was all going to come to a head.
Coming up with an effective solution isn't easy, as there always going to be 'killjoys' out there who want to live in a serene, silent enviroment, but with careful management everyone can coexist. But there are a few caveats that you should realise about noise before you start.
First off, tone is a big killer. You can make a LOT of random noise and it's not irritating. Think about dump trucks dropping their loads, it's dull roar and doesn't take much for it to be overlooked mentally. Anything with a tone though, is picked up by our brains, and can quickly become a nuisance, ESPECIALLY if it changes tone. Think about a control line model, and while the engine isn't changing RPM, as it whizzes around the circle, it appears to change tone... like a siren... and think about how quickly your brain picks out the sound of a siren!
Duration is another big factor. If you were to make a racket for 30 seconds, no one would care, but if you do it all day long, you can expect to have someone out for your blood.
Now it's not all bad. Being control line, we have the benefit of being reasonably close to the ground, so the issues of sound carrying a long way, (like with RC) aren't so bad. In fact a row of trees will mask the sound quite effectively (but make it interesting when the wind blows through them)
When talking to the lady, it might be worth discussing the idea of a management plan with her. It shows you're willing to come to the table with a solution, rather than just reacting. Most people are happy to at least hear you out.
In your management plan, you may want to spell out maximum engine noise levels (this can be arbitrary, everyone knows a loud motor when they hear one) and times for flying, and a conflict resolution path, i.e. if someone is making noise, she has a direct line to someone to complain, who can fix the problem, before she calls the cops again!
Flying sites are becoming hard to find, and harder to keep. Stick with it though!