This guy on the PFK did what you are thinking of doing with the liverock rubble/stones type thing... only his tank is 6ft and FOWLR.
Starting out...
Badgers 72x24x28 fowlr tank - Page 9 - Practical Fishkeeping Forum
Starting out...
Badgers 72x24x28 fowlr tank - Page 9 - Practical Fishkeeping Forum