Sub placed behind couch?

[Riff Magnum]

In my living room i would have the couch about 8 feet from the wall and there's a corner that's empty for it, but i'm actually thinking about turning my spare bedroom into the home theatre. It's smaller in there so i wouldn't be able to do it behind the couch, but i might be able to get away with a couple bass traps and some reflective/absorption panels on the walls and there's less light to deal with. I also like the idea of getting a smaller tv, but it still looks huge. Would a 58" be too big at about 8 or 9 feet away?