We have a 2003 IC 3800 dognose. Not bluebird (AmTran)
Ours is a 6-window. It measures 24 feet bumper to bumper.
Each window is exactly 27" wide to include 1/2 of the space between windows on either side.
Assuming everything the same, that would mean you could go a max of 7 windows before exceeding 28' in total length (8 windows would be a hair under 28.5 feet). I don't know what your flexibility is w/ that figure (can you be a little long so long as the tires fit on the pad, or do you need to be a little short in order to maneuver in & out).
Granted, this assumes exactly the same body style & door layout. We don't have any handicapped doors. It's an IC 3800, manufactured by American Transportation.