If you're thinking closet for stealth purposes, consider the space that the sound proofing you definitely will need is gonna take up inside. Where is your intake coming from? Are you using LED lighting? You may be better doing a wardrobe conversion and using a couple smaller dressers as clone and veg chambers. You can make it work for sure, but be realistic with your space. Why do everything in your one closet space when you could use it just for flowering and do a scrog/sog style setup, possibly multi level. That way you can keep your vegging plants extra short, which is perfect for an LED in a dresser setup. You will need a space for drying too, so consider that if you're thinking of doing a perpetual. Obviously I don't know your exact situation but that's what I'd try and do if possible. It's not difficult to setup a couple dressers with a filter. LED lights point straight siren down so I wouldn't bother with mylar and painting walls white etc. In such a small space with an LED your light coverage will be shit and especially if you grow taller plants you'll find yourself pulling top branches towards the middle to get bud sites under the light because it points straight down with almost no spread at such a short grow space height. Hence the sog idea in particular, I think you should cram as many small plants as you can in the closet. In my opinion.