Georgina,
Yes. Your 'naive' analogies are now very close. Half silvered mirrors will indeed split the 'signal'. The claim we can't 'divide' photons is a stupid assumption derived FROM the fact that we only find a signal on one path. My 2012 essay (last fig) showed an experimental result of an orbiting charge, like a ruby ring.
It's 50:50 which of any 'semicircle' the ruby will be in, but the WHOLE distribution is the ring itself. The ring really describes a helix, but looked at in 2D from the side a helix is a wave sequence. Strike a vertical line at random anywhere on that sequence and it will cut either through the positive or negative charge position. The 'manifestation' can only be on the positive charge path, but recombining the two still gives the 'self-interference' pattern. Again that's a simplification - but perhaps still too complex to easily grasp.
LET SLEEPING LIONS LIE
They don't work well as symmetry and independent rotation are required, but we can make the basics work if ghost is lying down, belly facing Alice (or Bob). She can roll over at random, and also, as you identify, rotate her orientation, so when lying along the A-B axis both A and B see 50:50 light/dark. There are also intermediate angles on both planes (lying on her belly at 45 degrees) but as she's not a sphere or torus this 'distribution' can't give us the cosine curve! The other problem is that we also need a 'ghost' Ghost who can be rotated independently of the first. If we can't do that, then we'd need to be able to rotate the 'picture' of ghost (belly to back) by rotating the photons, which returns us to nonsense!
The problem using Lions is the same problem as using maths. We can only make it fully 'work' by assuming some physically nonsensical effect or other. Nature is simpler. Just consider the Bohm case of a central Stern-Gerlach 'splitter' sending identical spinning spheres in opposite directions on the spin axis, one then seen as the North pole the other the South (each can see HALF of the object reality!) But the pole orientations are able to be reversed incrementally by the detector EM field setting angle without affecting the spin (giving each observers subjective reality).
Understanding that is like riding a bike. Beyond human capability at first, then entirely intuitive once learned. You're definitely getting there!
Best wishes
Peter