Can you post a picture so we can better visualize the issue? You can greatly tie a line around a square concrete piling unless you don’t have any tide.

You say the line is used to keep the boat off the dock, does it mean it s on the other side off the boat? If so you ll be better off with bow and stern tied to the floating dock on the side opposite the stairs. For the stern line if you can cross it across the stern it will be even better.

If you can’t tie up on the other side when big ball fenders will be you best solution to keep the boat off the dock