I resemble that remark!
What pops into my head when I see all that space behind your speakers is, bipolars. The spectrally-correct output from the rear-firing drivers will have a long reflection path and imo this is desirable.
You can do a test run with the speakers you already have, in effect comparing a single monopolar speaker with a single bipolar speaker:
Place one speaker in the middle of the room at your normal speaker distance, facing you. Place the second speaker maybe six inches behind it, facing the opposite direction. Ideally send a mono signal to each speaker. If you have a balance control, you can use that to effectively turn the rear-facing speaker off. Anyway the idea is to compare monopole (signal only going to the speaker facing you) vs bipole (signal going to both speakers). You may want to turn down the volume for the bipolar configuration a little bit so that it doesn't get an unfair advantage from the slight increase in SPL from the extra reflection energy contributed by the rear-firing drivers.
Of course this won't be a controlled blind test but imo such is not always needed in order to make a sufficiently informed evaluation.
If you find the bipolar configuration to have some promise, here's a link to an article I did for an online magazine about thirteen years ago. Some of the ideas are outdated but some of them may be useful to you: