> The usual way to handle this problem is to have the speakers way out into the room or have them soffit mounted. <
Moving speakers out into the room does not avoid SBIR, it merely shifts the first frequency in the series of peaks and nulls to be lower. Moving them away from the front wall does reduce the bass shelving increase for being near a boundary though. Soffit mounting does avoid SBIR.
> I'm not sure whether placing broadband bass traps in the corners behind the loudspeakers would help SBIR distortion at all (I'm sure room mode issues are ameliorated regardless...) <
I believe corner trapping does help, though I admit I've never performed that exact experiment.
> I was wondering whether there are unique benefits to having bass traps in the front corners of the room too. <
Yes! All corners are valid for bass trapping.
--Ethan