What about one of those nice outdoor cat enclosures?
Alot of folks have them, and would be able to give some more information, but it would allow her to get out and get some fresh air and run around in a pretty safe enviroment.
I am really against just allowing a pet to roam around. From a traffic standpoint, there many not be many cars, but it only takes one. On top of maybe causing an accident when someone would swerve when something runs infront of the car.
The outdoor enclosures may work well for you.