False Corner Wall Length Versus Performance

[Boydfp]

I'm looking a building a set of false corners for my Klipschorns due to an open floor plan on one side of my family room and protruding window seals on the other. I've read about every false corner post and settled on a design that copies the Rudy81 design: two pieces of 3/4" plywood sandwiching 3/4" MDF screwed onto a 3/4" MDF floor.

My concern is the length of the walls. In my email exchange with Klipsch they have made it quite clear that a 48" long internal wall is the bare minimum required to avoid deteriorating low and mid range frequency response. (Apparently the Dope from Hope article isn't accurate as it shows a 48" outside dimension implying a 42 3/4" internal wall based on the construction.) However, if my internal walls extend past 43" I'll begin blocking a recessed area reserved for a future built in entertainment center.

While I understand that 48" will provide better performance I have no idea how much I will lose by giving up 5" Any experience with shorter walls?

Update:

I met with my cabinet maker and he says he can integrate the false corner extensions into the future built in cabinets so I guess my problem is solved. I'm going with the full 48" walls.