To have an array, the system has to be coupled with the floor and the ceiling, and you have to be in the nearfield for listening. The nearfield is roughly 3 times the array size, which means that you would have to listen to the system less than 4 feet from the speakers, and the size doesn't couple with the floor and the ceiling. And even at this distance you would not be in the nearfield for the tweeter. So you are just building a large point source speaker system. I suggest you consider a D'Appolito MTM design with a couple of larger woofers at the bottom.

There is no such thing as a small array. You either have a line array or you don't.

Marlboro