Klipsch WDST speakers - closed enclosure - can be wall mounted, like most of the bookshelf speakers (RP-400/500/600), so you can push them to the wall, but if you can (or have to), leave some space behind them. It can be helpful if you use "back ported" speakers and won't cut them at 80Hz (so the air can flow at lower Hz).Getting rid of the shelf and I'll try the side walls first. Should they be as close to the wall as possible, or pulled away from the wall a bit?
Put them on the side walls adjacent to the MLP or a bit behind.
Sorry I don't remember which speaker is that, in your signature I see you have an RP-500M, but you asked about bipoles...
Edit: I see now, RP-250S, like my surrounds.