OK, here are my thoughts.
My understanding of what I am seeing.
You have two interferences:
- The bolt of the rear rack/fender on the frame
- The right side adjustment screw of the rear wheel.
1) For the rack bolt, I see two things you could try to reduce the interference.
Instead of a screw coming in from the outside with a big bolt on the inside, use a flat head hex screw (below) passed from the inside with a bolt on the outside.
Won’t be as pretty but should save you a good amount of space.
If that ends up no being enough, you could probably adapt the rack/fender bracket so it attaches on the outside of the frame instead of the inside, still using a flat head screw as mentioned above, that would save you the thickness of the bracket.
2) For the adjustment screw, my understanding of what I am seeing is that this screw does not really hold anything, but is mostly here to make the adjustment easier and more precise. Ultimately what holds the black dropout to the blue frame are the two big side screws (see below).
If that premise is sound, it means you could cut almost half the protrusion (using a grinder), keeping just the screw body diameter so you can still use the screw to move the dropout precisely.
That may save you enough space so that you could add a spacer on the right side and fit the hub.
If that ended up not being enough, I think you could probably cut the whole adjustment part on the right black dropout.
It would make the wheel adjustment more difficult but not impossible. You lightly tighten the two mounting bolts , then tap the drop out lightly to move it in until the wheel is straight.
Eventually you could confirm with the manufacturer that the Adjustment screw mechanism is not needed for structural hold of the dropout onto the frame.
3) Final thoughts:
The wheel may end up off center (sideways), but that can easily be corrected by adjusting the spokes.
If you have about 5mm offset or less, you can simply loosen the spokes on the left side and tighten the spoke on the right side to shift the rim right. If you have more, you may need to re-lace the wheel asymmetrically with different size spokes on the left and right. You do it one quarter turn at a time (same on all the left spokes, same on all the right spokes, and check the position)