Bob,
You should be able to work with that. The trick is to avoid doing any damage while you sort out the rest of the deck. I've had decent success on a few old decals. But, don't take my word for it. Rollin is the master of holding his tongue just right while cleaning the decal with a cotton ball (Q-Tips have not made it as far North as his shop yet) and denatured alcohol.
https://forums.wcha.org/threads/16-foot-skowhegan.18503/#post-96364
Once the deck is done and ready for varnish, varnish over the decal at the same time.