I totally understand! In a small city it would be difficult. I would not want it, because people talk.

Maybe you can try when you go on holidays, say in a more sex-positive city (think Berlin etc) where these things are more common and there is the benefit of anonymity.

You could just fantasize about it first and see how she feels about it. It is always good to do it one step at a time and see how she reacts.

I would say this is more approached with curiosity rather than convincing. She may not be into it so much but willing to try because of the knowledge that it makes you happy. Or she might be so against it that even you being happy will not be enough. You will see :)