I'd figure out how to mount some kind of
Stainless steel chafe guard to the
hull. A "rub rail for ropes" kind of thing.
Some stainless tubing welded to a plate with end plugs or tapered ends in the tube ought to
work. Your friend already knows how long they'd need to be and where to put them to stop the chafing.
The mooring line should just run across the tube like in the case of the towel, not through it. The tube just keeps the line off the hull, just like the towel should have. Size the tube and plate to ensure the line doesn't touch the hull from any reasonable angle.