I will have four behind the screen two stacked left and right of the center channel. One middle of the room possible two, and possible two quads or duels in the back corners of the room.Based on the information on the GX7 in this post yes that should work. Just remember you want the subs that are running together co-located or as close to as co-located as possible.
With a total of 24 12in JBL in the room. Six of the 12in JBL are in a boss riser platform. My understanding is I don't really need any Ultra low bass because I have the tactile from the BOSS. Also safer on the house staying around 20Hz?