Why not write the offending companies, and ask that they chip-in to install a dock-long ribbon of (something like) the below rugged plastic/vinyl material? I have a similar coil of tougher 10-inch material, but haven't needed to install it yet.
Bent into a semicircle every ten inches and lag-bolted to the dock to make a long undulating ribbon, it is an effective, long-lasting, tough, and inexpensive way to protect your dock. I'd ask that they extend the attachment points so it is flush with edge of the dock.
That they provide the hardware and install it—
indirectly getting "permission" to use the dock—it would be a Win-Win outcome.
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