I looked into the Bostons, looks like a killer sub.

Yet after all the trouble, I redesigned the box in CAD format, and it looks like I'll be able to get 1/4" clearance on my current Kappa Perfect 10 (5-3/4" mount. depth). I'll either be removing foam from the underside of the upper fold down compartment, or just compressing it enough to get a level armrest/table.

Thanks for the suggestions.