I get all this, but you've sidestepped the issue which is that you can't measure the light as a wave.
I Haven't at all the uncertainty principle part explains it. The evidence of the wave is inferred of course by the interference fringes. Measurement though makes the wave form uncertain but it does not necessarily say there is no wave form, quite the opposite in fact.
As I said whether you consider the photo back plate as a measurement is a moot point.
As I also said it depends on what interpretation you follow, you can see the evidence as deterministic and hence follow it back through the maths to the exact values and hence a backplate can infer an absolute reality with the wave functions extent, (wave function real, determined) or you can see it as stochastic and simply say the wave function is something unknowable. It all depends on your point of view. Both literally and figuratively in this case.
You can not of course directly measure the wave as I said for the reasons I said, but science is not bound that way. it can use inference too.
If physics only relied on exact measurement it would be dead now. The people who have developed these interpretations of stochastic or probabilistic mechanics and the maths involved, have though very hard about proof and evidence and measurement to the point where some have said inference makes the proof, and others have said that is nonsense. It all depends...
Wave/particle duality exists, it is not a mistake, it is not something anyone would argue about in physics. The essence of matter is clearly and provably both a wave and a particle, it shares the characteristics of both. QED
In essence what you seem to be saying, if I am not mistaken is no one has ever said or proved or shown light is a wave nor can they ever because of the nature of photons et al, this is of course false. Not just false it is clearly against all current scientific thinking. If you want to argue light is not a wave form or electrons or whatever, you are most welcome but the proofs and hence the evidence say otherwise.
If a tree falls in the woods and no one is around to hear it does it make a sound?
Think about it?