My ideal keyboard

I've been using enough mechanical keyboards to get a sense of what I really want. The features I want are hard to find in one place, though.

• Split ergonomic layout
• Unibody - hard to find unibody split keyboards. I find wrangling a fully-split keyboard a bit of a pain, especially when I have to move it about on a daily basis.
• Thumb clusters. The bottom row on the Atreus is /good/, but could be better. Only the inner three keys on each side of the Atreus bottom row are easy to reach with the thumbs. On the right, the outer three are kind of okay with the middle, ring, and pinky fingers, but they're a lot harder on the left for some reason. And even on the right, I sometimes reach nearer or farther than I intend for the punctuation on the middle and ring fingers.
• 60% to TKL key count. The 40% key count on the Atreus is low enough to make some things less simple than they should be; mainly number entry. The Atreus layout plus a number row would be satisfactory, though on my 60% keyboard, I /sometimes/ miss dedicated arrow keys.
• The 5 key per side layout of the Atreus is good; the 6th outer key on regular keyboard layouts is a stressor. The only really reachable keys on those columns are CapsLock and Enter normally.
• Columnar stagger. Took a little getting used to on my Atreus, especially when switching back and forth, but it's clearly the best compared to both row stagger and ortholinear.
• Clicky switches with a little extra force. Cherry blues are a little too light, Kailh Box White are good, would like to try Jade.
• Every key is either exactly one unit, or exactly two units in size. No custom keycaps.

The Arisu/Alice layout comes so close to being what I want. It's the right size (TKL). It's a unibody split. It has thumb clusters. The main things I don't like about it:

• row stagger
• The wide space bars take up valuable thumb space. Maybe one can be divided into two regular keys and be used for modifiers.
• The shift and control keys are way out on the outside column (though presumably if I could divide one of the space keys, I could use it for both). For Shift this isn't so bad, since it's paired like on a traditional keyboard.
• The Fn/Layer key is way out on an outer-outer row. Maybe I could move it to where they have Left-Ctrl.

The Keeb Iris is very close to what I want. Its only major flaw is that it is not unibody. I suppose you could make a unibody case for it, but it would have a fair bit of wasted space - unless you used that space for a trackball?