I did a bit of testing to simulate Cam's wall-mount layout with my M5's - right hand speaker in fairly close & pointing straight ahead, left hand speaker "way over there" and toed in significantly.

Worked better than I expected (eg better than my results with speakers closer together but not toed in at all) although only maybe 8/10 for imaging compared to current location. I ended up getting best results by only partially adjusting the balance control and letting the soundscape spread further to the left... thought that would be odd but the result seemed pretty natural.

All that said I think Serenity_Now's idea of smaller speakers mounted more closely could work even better than anything we have discussed so far, although you probably would end up wanting a subwoofer to cover the lower notes.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8