Polyester (dacron) will shrink ~15% with heat.
Install the skin as well as you can.
Heat to shrink (I use a heat gun at 1000F and haven't had a problem). You do have to not let the gun stop. Once you get it tight you will not be able to make it tighter with additional heat in another area.
Polyester will not stretch out when it is in the water like nylon.

This is really easy, but don't try to sew very tightly initially, it is easy to pull the fibers aside and make a hole. you won't have damaged the fibers, just pulled them sideways. With a little work you can release that stitch and move the fibers back.

Marc