I would add that planning to arrive at campground early might turn crucial.
I tried to reserve spot at Homer Campground, but per personal answer at the office - they don't even review the emails.
I made a point to arrive on Thursday 1 PM and was able to get "tent site".
Than Saturday 3PM at Seward, with several hundreds of sites along the waterfront, I catch 1 of 3 left.
So with law allowing staying overnight at rest areas, I rather plan to sleep on the road and arrive at the destination early.
We do have good luck to weather and here is Seward this afternoon