I think photons are more physical than anyone would be willing to readily admit. I would go futher to say that I don't think anything "physical" could even exist without them. I think the unified field theory could play a decisive role in this discussion. The fact that three of the four fundemenatal forces have been unified could be evident of an underlying mechanism playing a role creating or contributing to those three forces. Photons could in a sense be seen to just be tied up into different shapes creating the properties of other fundemental particles. Like when a quark is detected it is from the release of photons in a quarkscrew pattern (hence the name), but what about the quark itself and its physical effect on reality? It is just a certain type of reaction detected by photons. How do we know that quarks are not just photons quarkscrewed together, the fact of the matter is that we don't and we just have to explain them as a fundemental particle that fits into the standerd model that assigns certain types of reactions as fundemental particles. Physicist are unable to explain quantum mechanics in physical terms where they can make predictions of those explainations, but they are allowed to describe them mathmatically to make predictions. Without the mathmatics it would just be to complexe to explain, so the answer is that quantum mechanics just doesn't care what particles are truely physical or not and it does not tell us either one way or another. But, I would assume that the photon is a truely physical fundemental particle that has particle-wave duelity with a certain degree of uncertainty.