The rock should be fine. The driftwood helps aid in digestion with the Pterygoplichthys family. Also depending on the temperment of the cichlid will determine if it will work or not. In my my experience Rhino's tend to not defend themselves very much. They rather flee and hide which makes sense with the coloring and all makes for perfect camoflauge. In a tank though there is only limited space to flee to. Ive noticed gibbiceps are more willing to fight of intruders and so are joselimaianus. Weberi's tend to be very pushy as well but from info online don't get nearly as big. Mine are still young so only time will tell with my weberi's.
^ will consider
anyways, the cichlids are way into the future
