I wonder what is going on in your wife's mind? She's part of the DADT arrangement too.
Is she in denial, dreading what she believes will be the inevitable escalation and demise of your marriage?
Does she believe that things will remain as they are, providing no one spoils the status quo by talking about it?
Is the fear of examining her own beliefs and biases keeping her from talking?
Could your wife be quite insecure and believe that she would have to address her own issues?
My wife has some insight in this matter.
She believes that since there is no requirement to provide a real answer to a hint or a joke, you won't get one. Instead of the indirect approach, she believes you would have greater success with a direct approach. Make sure that she knows you love her, respect her, and want to spend the rest of your life with her. Let your wife know that hiding and sneaking is tearing you up inside. Tell her that you want to be up front and honest about your crossdressing. Say that you don't expect her to embrace this part of you, but that you want her to accept that it is as much a part of you as your eye color, and like your eye color, it won't go away. Let her know that you want to have a frank, open, totally honest, and ongoing conversation. It bears repeating that you set her mind at ease regarding your love, respect, and commitment to your marriage. Without that, she is right to expect the worst.
Expect the conversation to be difficult, maybe painful, and lead to a better understanding.
Best wishes
MsVal