With the current stand it will be hard to make towers work. May want to consider Kef R300s as they have the separate woofer or stay with the CM5s and add a sub which you can control the bass level separately. Even a front ported speaker will have issues stuck next to a wall I would think.
Edit: For your room stand mounts may be the best option. Add a CMC2 and a sub to your CM5s. What split for music / home theater and what is your priority?
Main Kef: Reference 205/2 & 202/2c, Surrounds: Kef XQ40, Velodyne Optimum 12, Integra DHC 80.3, Ayre K-5xeMP, Oppo BDP-103, Bryston 4Bsst2, Parasound Halo A31. Second B&W: 685 (3), CCM618, Def Tech Powerfield 1500, Onkyo TX-NR1008, Zone 2 Klipsch AW650.