I'm going to apply it on my plylining when i get it done.
I did this also, I did mine about 1' up from the floor.
But what I did find was that about a month later the ply lining above the protectakote started to grow mould because it was such a damp environment, so had to sand it down a give a coat of clear varnish.
My advice might be to treat the bare wood with some clear varnish, looks better than a mouldy van.