How to smooth out wrinkles in door panel vinyl

I made a new door panel backer for my 68 New Yorker and I'd like to to put the original vinyl onto it. It has no cracks or tears but there wrinkles on each end of it. I have to be careful with it because it it does not feel super soft and pliable. It feel like too much manipulation will cause it to crack so I don't want to just try and stretch it. I'm thinking of gently heating it and using something flat and heavy to work out the wrinkles. But would love to hear if there's a more...

How to smooth out wrinkles in door panel vinyl
Author: WissaMan