Haha. I don't recommend the "stealth approach". I handle the finances, but my wife know what is going on. I just let her know when I am ordering something. She knows that I wouldn't jeopardize our financial situation for shoes, so she doesn't give me much trouble.
We have joint finances and we each set aside money from each paycheck for "fun money" as we call it. We can do whatever we want with it, so I save it up and get shoes when I have enough. She likes to spend it every week.
In my mind I envision it the same way. I don't think the stealth mode will be necessary as I'll be much more conscientiousness of both of us.
Plus for my tool collection shes ok with it as she hasn't had any vehicle repair bills in a long time.