I've since filled the far left and far right with S2's and Jupiters. Also added #11 which is the start of the opposite facing row of 10 more racks. 20 racks is my goal. The DC was nice and gave me an extra perforated tile row in my cold isle.

I do have to say it's quite nice to have the S2's on battery and generator, since an unannounced (or planned for that matter) reboot often leads to dead SD cards. All together the 11 racks are 100% full and I'm using a total of 21 30A 208V circuits.