It looks to me that you're asking is there an epistemological approach that can give a rational basis for selection one set of ontological assumptions over another. I'm not a philosopher, but I haven't heard of any theory or system of thought that explains both the materialist and idealist positions; the two are quite distinct systems, and both are based on assumptions that cannot be tested or verified within its own system, and apparently, cannot be resolved to the satisfaction of anyone outside each system. So, my answer is that I don't think there is, or even could be, evidence that would allow one to choose one system over the other.
The assumption that material reality actually is an illusion cannot be tested, because no matter how refined and detailed and consistent our study of the material world is, it could be evidence that the illusion of material reality is really just very refined, detailed and consistent. No amount of material evidence can show that it ISN'T "just" an illusion.