Yes, I'd try what Raptureready suggests. If you have an ironing board cover with a measuring tape cover, it would be even easier. Lay and straighten the first damp one and pin down very well. Then position, straighten, stretch as needed, the second on top of it and pin, and so on. Remember that wet fabric will stretch very easily. Try it with one set of 4 squares and see what happens.
I had a baby panel that had a terrible WOW in the middle and this technique worked for me.