While bcache isn’t officially supported by Rockstor, we do have several users who have used it and probably are currently using it; it should thus be recognized by Rocsktor. I personally haven’t tried it, though, but I would point you towards @phillxnet’s notes on it below:
Please note, however, that these notes are now a bit old, and I’m not sure of how much difference (if any) there would be in our new openSUSE base. I would thus point you towards a more recent post by @phillxnet with some bcache mentions of interest:
Hopefully some current bcache users can chip in here to provide their input as this would be more helpful to you.
In any case, good luck with your endeavor, and I hope I was able to at least give you a few interesting bits of information.