I know this is an older thread, but I had an interesting observation about SMGG last weekend when I was riding it. It's much less "scary" from the last seat. Most of the projections seemed to time better with the front of the car, so by the time the back of the car reaches the scene it's over.
For example, in the launch sequence, if you seated behind someone taller than you, you can't see anything except the lightning on the side walls.
Inside, when the clawed hand "chases" you, it chases the front of the car, so the back of the car doesn't see anything until the hand has stopped moving.
Also, when the ghost lunges toward the car, it's finished lunging when the last car passes under it.
So, while the ride is more "intense" from a movement point of view in the back seat, the projections are much less "scary".