I'm leaning towards just getting a bunch of BTAs and hoping the ocellaris take to them later on. But, just in case a H. Magnifica pops up anytime that fits the bill, I have some tonga shelf rock. One piece is about 9" x 7", which I think would both fit my tank and a smaller magnifica. So I put a smooth layer of TLF aquastick putty to smooth out the surface. Once it cures, I have some small rock rubble pieces I can then attach this piece to my current rockwork to make a pedestal for a mag.
I also have that gigantic piece too, that's about 15" diagonal. It probably would just shade everything on one side of my tank, but I'm keeping it for any possible tank upgrades for the mag.