ooooooooooooo river nice... i think you can fit a nice tang in there and dont be silly you cant put an elephant in there be realistic.
Why go with Tunze when you can make your own surge device. I think around 40 gallon with 2" pvc should be adequate. My other suggestion is to have a plastic rain gutter around the tank so that when it overflows, the fish and the water can be returned back into the tank.
An RK2 skimmer and a 1000 gallon horse-trough style refugium should be enough to handle your bioload, along with a 600 gallon remote sump for added volume (even buried underground to provide cooling for the 6 solatubes and 1000w halides that light your tank).
Jerks, just go "ooooooooooooo river nice!"
My other suggestion is to have a plastic rain gutter around the tank so that when it overflows, the fish and the water can be returned back into the tank.