I concur with clgpalmer and I am surprised to see this mentioned after 9 posts, actually I find it sad.
I am sure as a woman she will blow up and get VERY INSECURE but reassure her it is for you and you wanting to please her, I told my wife I have wanted more far before I met her and it is a self image thing. Needless to say don’t think you will tell her and have her say “okay honey” and walk away but if you are open with each-other otherwise then tell her or else she WILL blast you with “why do you need to sneak, what else are you sneaking”, I find telling my wife most things cuts nagging and other noises that come out of her mouth at least 50%.