Subwoofers and Seating Position for Klipsch Forte iv's

a lot to think about. I think the crawl method might be best.

I completely agree and was hoping you’d be up for that.  The other placements are just general guidelines and may or may not work well/best in your particular room because every room is different, so the crawl method at least ensures you’re getting the bass tuned specifically for your particular room — it just takes a little more effort upfront, but it’s one and done and well worth it IMHO.
 

@ noromance  +1

1. I will second using a distributed bass array if you really want to improve low frequency quality.

2. I would also try moving everything further out from the front wall. Perhaps 8 feet.

3. If you do stick with two subs. Put them where they sound best, as opposed to where they look nice.

After reading OPs response, I think I disagree with Tony on every one of his points-  

1. Clearly there is a budget in mind as well as certain esthetic requirements that adding pile of bass speakers would be prohibited for multiple reasons. 

2.  Having speakers far out from the walls is seldom the best location, usually results in weak bass when applied to full range speakers, and ruins the feng shui of nearly any living space. The only types of speakers that I've heard that really benefit from being way out from the walls are dipoles. I have the Forte IV, 6-24in enough room for it's passive radiator.

3.  Subs, or more specifically bass, is omni directional.  They are also adjustable in output and phase so they can sound good in a location where they also look the best. 

The best audio systems that I've experienced are typically among the most visually appealing as well.  There is nothing worse then a carefully pieced together system that looks like a showroom in an audio store (the exception being showrooms that take the extra step to stage like a living room etc). If its in your home, make the system work around your space, not the other way around.    

Having speakers far out from the walls is seldom the best location, usually results in weak bass when applied to full range speakers, and ruins the feng shui of nearly any living space.

@perkadin  It depends what you mean by “far,” but go to any audio show or high-end dealer and the speakers are always well away from the walls unless they’re designed specifically to be near the walls, but those speakers are few and far between.  But point taken that going too far can result in negative results as well so it’s all about finding what works for someone’s specific tastes, speakers, and room.
 

Subs, or more specifically bass, is omni directional.  They are also adjustable in output and phase so they can sound good in a location where they also look the best. 

This is just factually incorrect.  To get subs to work best within a room they need to be placed carefully so as not to excite room modes and provide even bass response, and output and phase can’t fully correct for that.  Even if you use room correction that can’t do much if anything to improve room nulls — only proper placement can do that.  Just because bass is omnidirectional below a certain point does not mean you can just plop them anywhere — the room dictates where subs sound best and that just takes some work to get right unless you do something like a Swarm as mentioned earlier.

are you planning to match 2.5K subwoofers to 5K speakers that already have a lot of bass?