Interesting concept, that revival tank. I have to say, though, that i can't really see the point in it. If an angler wants to revive a GT, why not just put it back over the side and revive it boat side as soon as possible after a couple of photos?
The only scenario I could think of that you wouldn't want to release the fish immediately was if there was a ravenous pack of massive sharks at the back of the boat. And even then, the sharks would probably follow the boat to wherever you wanted to release the fish?
Anyway, that's my take on it.