Congrats on doing the PCT. That's one *heck* of an accomplishment. Sounds like you should be able to do Skyline from just a fitness perspective. I was keying in on your bad knee and how much weight you'd be carrying up what is essentially
five Devil's Slide Trails back-to-back. Just didn't sound like fun to me.
As for the route itself:
Originally the Skyline trail was truly a trail built by the CCC in the Great Depression. It then feel into disuse and became more of a route. In the last 10 years it's become popular as sort of the ultimate hiking challenge of Southern California. The path is now a lot more well worn, but there are a lot of short cuts and such.
I read about people getting off on the wrong path and getting confused. I also read about people who say that the route is pretty straightforward. I'm not sure what to advise someone looking to try the "trail," but for sure don't expect a well marked, well maintained trail like the PCT or Devil's Slide Trail. Skyline is unmaintained and is just kept alive by the passage of feet. Yeah, indefinite answer, I know,

but that's the best way I could respond.
Hope that helps,
HJ