The base is pretty big on the NX-MTM's. I'd have to open the file to get exact numbers but, it's roughly 9.5" at front, 16" at rear and 16-17" deep, it is 1" thick ( at least the ones we were cutting0.
With the higher c/o point to the subs , you do want to keep them inline or as close as possible to the subs which was why the dual h-frames were recommended in the other thread.
jay