Side sponsons gave me an idea --- I tried something y/day-- while gluing in a pvc sea-sock in my SeaTour.
I covered the gunwale just aft and fore of the cockpit area -- which has the most wrinkles-- with some thin tube foam -- the black stuff used for insulating pipes, and find the wrinkles smooth down substantially.Something to do with the "stress" points of the wrinkles having more cushion??

Let me experiment some more ...

Will post an image shortly.

Cheers

Prasad