Hm...
It seems like using a reference there is not the correct way of going about things then? I guess I'll look up how one would usually pass an object to a function. I didn't write the WaveHC fat lib, and the SDFat lib works a bit differently and has the open function declared differently which allows it to work without the *.
This is how that lib handles it:
bool SdBaseFile::open(SdBaseFile* dirFile, const char* path, uint8_t oflag)