You can't bring the left speaker forward, and move the right one to the left? Townshend Podiums are no bigger than whatever is under them now. Any sort of springs will both improve imaging and reduce sound going into the floor and bothering neighbors. But nothing really will give you stereo other than moving to where everything is somehow equidistant and symmetrical. Not with the room just with you and the speakers. That one requirement is what we call non-negotiable.
Your problem is not being equidistant its always going to sound like 2 speakers instead of a sound stage. Adding a center channel will only prove the fallacy of HT, because you will still not be equidistant so no sound field only now it will be coming from three instead of just two. And the HT processor needed to do this will only ruin stereo. HT is what we call a lose-lose proposition.
Your problem is not being equidistant its always going to sound like 2 speakers instead of a sound stage. Adding a center channel will only prove the fallacy of HT, because you will still not be equidistant so no sound field only now it will be coming from three instead of just two. And the HT processor needed to do this will only ruin stereo. HT is what we call a lose-lose proposition.