How far and wide? NSMT speaker placement

I can relate. My room is about the worst shape possible 16x16.5 :-( Monitors do a better job of soundstage depth in this room, but at present I have a pair of too large Zu Omen Defs. Wide but shallow stage nowadays. But I really really like the sound they provide. GIK room treatments and three subs make the room respond as well as it can I think. They are positioned rather oddly for the best sound - the right speaker is toed out slightly, firing towards the opening to the kitchen. The left fires straight ahead though another door opening,effectively making the room larger. Sort of. There's a stable center image and instrument placement.They are each about 3 1/2' from the side walls, 2 1/2' from the front wall.It's like sitting just a few rows back from the stage. I listen mostly to acoustic and electric blues so it's a good setup for me.

Equilateral triangle with speaker faces aimed at the listening chair is usually a good starting point.

Every room is different. I think my speakers are out four feet or so. Mine Sonus Faber speakers do well in my room with a 8’ equilateral triangle.

The imaging stopped at the wall until I hung a thick wool carpet on the wall behind the speakers. Then the imagining went back behind the wall. The absorption from bolsters along the floor / wall junction improved the imaging even more. You can see photos of why main system under my user ID. 
 

But every room and speakers are different. The place to start is probably a 7’ equilateral triangle as far away from the front and sidewalls as you can. “Cross the streams” 18” behind your head to start with toe-in. Then move out to perpendicular to the wall to stain the best soundstage vs central focus. 

I use angles and have front left and right channels at roughly a 30 degree angle from my MLP. Because my room is a bit narrow I needed to bring the MLP forward to about the center of the room. See:

@simonmoon 

that is cool!!!  thanks for including pics