I made one for my DGS that his mom asked me to do. It was a favorite t shirt that was starting to show signs of wear and they wanted to preserve it. I used an iron on backing, I think it was called iron on fleece that I had on hand. I'm away from home right now so can't go look at it. It was heavier than I use on t shirt quilts. Anyway, it turned out so nice. They were really happy with it. I made an envelope style pillow with a soft corduroy for the back. There was a small logo on the shirt that I turned into a pocket on the back of the pillow.
So a long story to answer your question, I would say yes, use some type of interfacing
