I really like this idea! This could definitely add a wee bit more strategy to the game, as well as being able to look completely BA. It could also make it more risky adding larger items to your backpack, like having a shotgun, so that you'd be more of a target. Also, it could make organization more important, because depending on where you put the item, it might stick out. Although some people wouldn't like that, because, you know, organization.