If you were to be honest about 3 comfortable legit sweetspots that are not compromised......Multichannel - 3 concentric driver TAD standmounts for example, where one serves as a substantial center channel.
Or there are some high end pro audio speakers like Meyer Sound that have design tricks w.r.t phase characteristics, etc (if you were to try and stick with stereo)...
You will need to fine tune side wall treatment, etc.
In summary, it probably won’t be cheap, any additional sweetspot can get expensive.
I have my system set up perfectly for a single person sweet spot. Near field about 9 feet from my speakers. But if I move even slightly off center the soundstage moves and one of the speakers dominates. If I have a couple friends over how can I arrange my speakers so we can all get a good soundstage with centered imaging? Move my speakers closer together?