"Here is one option. The watermelon block is oversized. so I’ll have to figure that out."
How about you put the watermelon block on the back (as a label?). You could put it on point there (if you like). And add label info (made by; assembled by; date; etc.) using fabric marker or embroidery in the white "logs" of the block.
It will be a nice quilt, and bring you memories and smiles every time you look at it. Have fun with it.
...dany