OK, I found the photos in the
Cockpit and Accessories Album.

Here's a multi-purpose boarding plank build by Yellowstone John which is shown being stowed on the cabin top. Note that he has added an extra set of wooden rails on the roof outside of the OEM stainless ones.

Here the plank is deployed on the bow to reach the shore. If the anchor and roller are in the way, one might have to design it to set off to the side somewhat . A rope sling or loop holds the plank to the bow. The plank is 9 1/2" wide and 79-81" long and about 2 1/2" thick. It is made of plywood on the top and bottom, with solid wood sides, and foam filled for rigidity and reserve boyancy. It has been treated with a special wood finish of Dutch origin, but not fiberglassed. Weight is 33 lbs.
The grey material is 3m non-skid. Metal reinforcing has been added to the sides for stiffening. I've not seen it deployed in person, but wonder if it can be put over the bow right after beaching the boat, or whether on the first landing, one must go over the side, then deploy the ramp, being able to use it on subsequent trips on and off the boat at the same spot.

Here we can see the plank used to board the stern of the boat. It can also be used to board the boat from the sides, although we have no photo of this useage. A very versatile accessory!

Here's the stern of John's boat, "The Far West". The plank makes a seat as you'll see in the next photo. Here you can see a wooden panel with aluminum edge molding that fits into another aluminum three sided molding to form a barrier against the fine art of being accidently "pooped" on by a large wave, or when backing down in a following sea.

Here's the plank hung across the back of the boat, doubling as a seat while being stored there. You can also see the aluminum channel that holds the barrier across the engine well in place. Sorry about the green part of the photo. Can you improve on this great project design or come up with your own?

C-Dory boarding plank/seat
I hope all of this makes sense. I asked John about the projects at Shasa Lake in about 2003, then he sent me photos and a written explanation. Larry H scanned them into the Cockpit and Accessories Album, and I then wrote up the narration based on John's letter.
Joe. :teeth :thup