Use near-field placement to take out room size as a factor. Why not replace that table behind your listening position with a sub? I have outlined it with a red circle:
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Replace that table with a nice looking sub. Look at the Outlaw Audio Ultra-X12 or the Arendal 1723 1V. You can put a tablecloth on them to keep the room looking nice. Use a wireless sub signal transmitter to avoid wires altogether. If you really want to go nuts, replace that little table between the sofa and the armchair with
this sub. Both seats get blasted with high quality bass, and you have unlimited headroom since the sub is so close to you. The dual-opposed driver configuration negates cabinet vibration, so you can rest your drinks on the sub without worrying about them vibrating off the top. It's the perfect end table subwoofer.