It would seem what you really need is not a formation, but 3 single-planes flying together hitting the same target?
Mach, you cannot take out an HQ with 1 single formation. Not even if you hit every bomb (which Lusche has shown you cannot do, especially with formations). The required lbs of explosives is about 2 formations' worth of lancasters, last I checked.
Lusche: Have you tried the 4x 4k with a formation? What's the spread on that? Less ord overall, but still 16000lbs per plane. Less bombs = less scattering, right? Less line-in-the-sand carpetting, in and out and gone.