Pretty Pattern. I hope you get if figured out. I have not made a Bargello, but that particular design has a definite pattern. Look at these directions for an Quick Trip Around the world.
http://jellyrollsfabric.com/wp-conte...-The-World.pdf
Although the sizes of the strips are different, the pattern is very similar to the top half of a Quick Trip but with neutral outside rows. Personally, I probably wouldn't sew into a tube, I would just adjust my rows to match the pattern picture, adding or unsewing fabric at whichever end needs it. I hope I haven't confused you totally. The idea of working from a tube would strain my patience. Especially with a small quilt like this.