If you want to minimize vibrations, I wonder if you may want to consider the Linkwitz-style W baffle - in which the drivers move push-pull, in the arrangement shown there is still a force component that doesn't cancel.
Even so, I don't know how well that would work for your planned use - you may have to build them and try them. Perhaps consider decoupling the sub cabinet from the furniture around it? I think I saw someone do something like that here recently.