I agree with you. Men often underestimate what women actually know. And what they are willing to accept in a man they love. While a man might not want to bring up the topic of being a sissy or being bi, it is always bet to view our women as silent partners than as ignorant of our desires and activities. Keep your respect for your wife and she will be a better wife to you.Are you sure she doesn't know? she likes to dress you in lingerie and put on makeup? I think she might already know, or at least suspect, she might be pushing your boundaries seeing how far she can push them.
Have you tried telling her about your desires?
If she's interested, and open to the idea, try watching some porn like the situation you have described, make sure its amateur so she can see real people doing it