I appreciate the effort you put into this and the mockups really help to visualize what you are going for. However, I think very differently about two assumptions that form the basis of your redesign.
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I'm not sure how successful I've been in arguing my case, but I feel you focused way too much on the feats maximum (that pretty much was the least important aspect of the redesign). Like, the feats could kept at 4, with the other 4 becoming notes, with the notes being (optionally) converted into more feats, or more class features space.
The main goal here was to prevent back and forth shuffling between pages 2/3, because the inventory's spread over two pages (both for regular and for magical items), and "character details" also spread over two pages. Personally, I can't see how anyone but low level characters could only make use of two pages, if only because combat conditions are on the 3rd page and the inventory on the 2nd page is so small. As soon as you run into a monster with something special, you'll need to check the 'conditions' on page 3. And as soon as you find something that's not a +1 item (e.g. Necklace of Fireballs), you'll need to make use of the "magic items" on page 3. Likewise if you get something like a horse/cart and load it with stuff ("Other holdings"). So the minimum pages to me seems to be 3. Our entire group (Eldritch Knight (me), Warlock, Rogue, Wizard) switched to using these sheets, and everyone of us always keep shuffling between those three sheets because of the above. The only one that doesn't see much use is the 4th one. So this is not just me speaking here
But if you still insist on a minimum of two, then some things would make a bit more viable.
1) Merge Proficiencies (and keep 9 total) for a longer Class Features section. You ran into length issues earlier, and that would help there.
2) Make the inventory on page 2 bigger somehow. The current one can only have 35 items, and that is extremely limiting.
* This could be done by having those "51-100 lb" boxes use smaller fonts so they span one-line only, thus use smaller overall boxes. Heavily encumbered text could be reduced to "Dis. with Str, Dex, Con based rolls".
* Make the PP/GP/EP/SP/CP icon small and move them in the coin boxes themselves.
* One-box the lifestyle. "Comfortable - 2gp/day"
That should at least let you gain 3 lines, so 6 items in the inventory.
3) Add weight fields to armor/shield/weapons info on the 1rst page. This would save you space in the inventory.
And some other suggestions could still be incorporated. Like movable magic items. (Same for the attuned items on page 2, could be movable within their own section). And adding a weight field to magic items.