This is what I worked out in EQ7.
The plain colors are the background colors of the shirts and the stripes are a good representation of the striped fabric I bought.
Those little plain squares in the sashing are small logos that needed to go into the quilt and that was the best place to put them.
I ordered some blue fabric for the backing and that might go where that blue fabric is at the bottom of the vertical row on the left. I have to see how it looks.
I plan to quilt this in sections. The left section will be the border and the row of T shirts , the center will be the T shirts with the long sashing strips on both sides and the right side section will be the shirts and the right border. I like to do some quilting in the T shirt squares by outlining the motifs and writing and it is so much easier doing the quilting when the sections are a relatively narrow width.
I am still deciding if I will add the top and bottom borders as part of the sections and have long vertical borders or if I will add the top and bottom last for the long horizontal borders, which is the way I usually add my borders. Adding them last is more work for this quilt and that extra work would be two 65 inch lengths of hand stitching as I do the finishing on the back by hand after I put the sections together. I can think about it and make that decision when the backing fabric gets here.