I'm in the process of setting up my 5.1 system, and realized I don't have enough room to have the rear surround speakers more than a few inches or so behind the listening position. Will this adversely affect the sound, specifically for watching movies? As far as I am to understand, optimal rear surround placement is a few feet behind the listener and a few feet above the ground, to accurately reproduce 5.1 surround.

Any advice/experience would be appreciated. I don't have many options as far as space, the distance between the couch and the TV is very small, I could set the speakers high on the wall and angle downwards, the only other option would be to move the entire setup to a larger room in my house, which would be a last resort.