I agree, might as well put a big bright sticker on the window saying "Alpine" or "Kenwood", etc....
Back in my high school days kids used to put those big bright stickers on or just build a box like the picture above. Next thing you know, they would be crying "Someone broke my windows out & stole my system". I believe the stealth box is an awesome idea and investment to protect what shouldn't be seen by all.
Oh, van eyes allows you to see out really well, but allows people to see what you have in that rear cargo area too....just something to think about too.