I made a baby shower one and I was making a small ship with sails. The ship part is the one that was signed. I did not tape it off and some wrote into the seam allowance. You could use the same method but make the ship bigger.
Another idea is to make the snowball, that way there is more area to use for signing, and make it big enough that the family can sign and make a special block for him. Maybe use the school colors. Happy quilting.