[untamed]

I'm not a big fan of the look of powerheads in the tank, so that is the other side of the discussion.

The way I approached it, I built a circulation system based on closed loops with the thought that I could always add powerheads later if I wanted. You can't add the CL later...
So far, I haven't added any.

The end panel looks straightforward...One 2" intake and 4 - 1.5" outputs. My CLs run on a Dart pump and each output is actually only 1". I don't think you need the 1.5" outputs. The OM4way outputs are all 1"...not 1.5", btw. I like how you have the outputs high and low. I don't think you can go wrong with the sequencing. I would fire the two low ones, then the two high ones...

I see the same idea on the back wall...but I'm not sure what the fifth 1.5" bh is for. Again, you probably only need 1" outlets for the OM4way.

Your challenge is going to be to get good circ in that front right corner. There is no reason that you have to put all your outputs on the vertical walls...you can put them in the bottom as well. In my case, 4 of my 8 outlets are actually on the bottom. The trick with placement in the front right is to still make the outlet hidden from view.