If someone wanted to add doors to it, I just whipped out a 40 footer that could easily replace the ones shown or be used as scenery. I may or may not add doors and stuff to the ends myself tomorrow. I just can't be bothered to put it through UV mapping, baking, blah blah blah this week.
The external dimensions from connection pad outward faces to other faces are exactly 8' 6" x 8' x 40'.