No the back seat is still useable. I just have to take the front section out, and put the seat bottom back in. I have it set up that way now actually. Ill repost those pics from that link soon.
Thanks guys. Its turning out to be a really nice item. The storage and separation of stuff in the back is nice, and I have a completely open platform on top for anything else. Right not the back seat is in and just the rear platform is in and its working well.