I like the way you are thinking about it. Watts per sq ft. I'd dial down those things some though. Tent growing means headroom resptrictions, and you can push them softer but get the same results by keeping them closer to the plants.
Oh yeah, those 4xQB HGS style lights packed in there are gonna block a lot of airflow around the 5mm thick "heat sink".
Maybe consider going with some of the new "strip" style.
If you bought last year, I can see just doing QBs, but a year or 2 from now, nobody's gonna be buying QB288s. The strips just have too many advantages.
It's gonna be a strip world (and all I have is QB288s
)