Having stared at all the photos and that gif for a long time, I'm beginning to see how at least 3 decks could fit over there. The 2 deck set-up simply doesn't match very well. Although I'm still trying to picture in my mind how the ship works out to be 700+m (although I'm confident it is), it just doesn't make sense as a 300+m ship.
I look forward to more of whatever you guys can dig up.
Now I went to look at the windows of all the Enterprises to get a feel of how many decks fit in them...and my goodness, none of the ships are perfectly in-scale with each other. It's like they adopt a new scale for each Enterprise!