Using Integrity Streams implies ReFS (can't believe I didn't mention that word anywhere in my post... thought I did). StableBit Scanner doesn't support it AFAIK. And if/when it does, if it detects a hash mismatch without the drive itself being damaged, would it know to replace the data from the mirrored drive? That's where the SS+ReFS+mirror comes from - SS will detect and fix errors in the data automatically.
I'm just looking for a way to lower the amount of layers on top of the data. With the mentioned solution, there would be DrivePool on top of SS on top of ReFS. Having DrivePool handle the duties of SS would be the best solution, but I'm guessing ReFS is still a bit too complicated to fully support.