One problem to solve in making an enclosure,would be a quick connect wiring harness of some kind that would handle five sets of wires. It is time consuming to wireup five speakers,and impossible if enclosed. There has to be a way of disconnecting the sub from the speakers that is quick and efficient.
Bernie

A pluggable terminal block should do it.Now for an enclosure.

Similive,

The speaker sitting atop the sub is the center speaker. As for stacking V/S putting all the speakers on a single platform at the same level, I don't know if there would be an advantage or not. This is something you'll just have experiment with.

And, as you can see, both the 2200 and 5500 can be used at the same time. That's one hell of a lot of speakers puttin out lots of sound.

Gary