I've done one large T-shirt quilt from start to finish at someone else's request. For me, there was this awful moment when I was deconstructing the T-shirt and cutting the logos: I felt like I was cutting someone else's memories apart! I backed the shirt logos with fusible interfacing, pieced and finally loaded on the longarm with 108" backing, the lightest batting I could find, and meandered allover around the logos. I didn't want the backing to stretch like it sometimes does when quilting a pieced backing, the Hobbs polyester that's used for clothing is thin but strong. and meandering worked to hold it all together nicely. It was still heavy but the recipient loved it so I'm counting it a success. Have fun!