My friend made a signature quilt for my daughter's wedding and it was small, just about 20" x 20" and just the parents and wedding party, of course, the bride and groom signed it. She has it hanging in her kitchen. It was made before the wedding and quilted and we had no problem signing it. Just an idea for you.
For my DIL's baby shower, I had people sign a piece of fabric and I made that into a quilt. It was the sail boat and the signatures were the boat itself. That turned out good too.