I wouldn't use either. Those are more for applique. I'd use either a stabilizer or iron on interfacing. Many people use the nonwoven lighweight interfacing. I used the fusible tricot, applying so the stretch of the tricot is the opposite direction of the stretch on the t-shirt fabric. I was very pleased with the result.
Sorry, just noticed the LazyGirl one was interfacing. That might work.
Also, don't worry about the size of it, you can always use 2 pieces and overlap.