I still wonder if the bass will be uneven in a room that size. The SVS or Rythmik may not solve that problems. Chase makes an SS 18.2 that will have more output than the two other 2 subs but it is larger. Even smaller multiple subs may give you the bass that your are looking for since you are not looking to get to reference level.
Klipsch RF 7 based HT 7.4, Pioneer SC 35, Acurus 200 Five, Dayton 18 Ultimxa Dual Sub Cab(2), Dayton 18 Ultimax Large Vented Sub Cab (2), on Berhinger I Nuke DPS amps, Samsung BDP F 7500, Asus/My Book Live HPC 4 TB
Yaquin VK 2100 amp, McIntosh XR 5 speakers, Samsung BDP F 7500