I have enjoyed reading all the communication on this post. Beautiful vessel you have but I am a bit confused if you are trying to board from the side or the canoe stern. It would seem to me that you could tie your dink along side with the dink now laying alongside of the mother ship. One thing sort of stable...
Mystic Stainless makes a ladder that mounts to your rail and folds down, in a zigzag fashion extending as far as you need. There are hold offs for the ladder itself so its sits out from the hull. When folded up, the ladder can be tied or attached to the lifelines so it is tidy and out of the way. Since it is always attached to the rail, it is fairly easy to extend and pull back up. It seems to me that you could let is hang down when away from the boat by dink for your return since it seems that you would not be able to reach up to pull it down once down in the dinghy.
Mystic Stainless has a nice web site where you can view their products. They are not inexpensive but the product is of high quality and can be put on either side of your vessel. The fender step is a sweet, easy solution but seems too short for your needs.
Good luck in your problem solving. That is one of the things that make boating so much fun.
s/v Tango, Cabo Rico 34
On the hard, Lankford Bay Marina
Chester River, MD