Looking at your tank again, and ignoring the lack of machinery, my one real gripe with this rockwork is that it leans against the back of the tank. I always liked have at least 3-4 inches of space between the tank walls and anything.. be it rock, corals, etc. I like clean walls, and it's not possible to get a scraper or magnet cleaner with the rocks as you have them.
As suggested by others, have you considered pillars, islands, etc? You can do any of those (Using smaller rocks.. you could just take a hammer to yours if you wanted) using either adhesives/putty, or rods to keep the rocks together. I prefer the ladder as I like to have the option to disassemble if need be.