Alternately, put two subs (fed the same content) on front wall at 1/4" width positions, and sit ~2/3-3/4 of the room length from the front wall, centered between the left and right walls. The front wall sub placement attenuates or eliminates the worst width modes (as Floyd Toole noted
generally, not specifically for a square room) , while your seat position puts you between the worst length nulls and peaks. Theoretically at least. Real world in-room performance can differ.
Like many contrarians, you seem angry. Perhaps type more slowly?