If you keep a clear vinyl "window" so that the instructions and the CG rating are visible, I believe it's okay to recover with sunbrella, and you can use better webbing straps than the originals. If you're worried about the CG, maybe buy one new one, but the closed cell foam lasts a very long time. I'm still using ones from our first Insatiable, 25 yrs. old, and the sunbrella's still pretty good. Did not bother to recover them to match the color scheme on this boat
either: they're blue. And, basically, you can still toss them, if someone needs them, it's more important to help a person than to follow a regulation, IMO.