If you use a dock with a narrow slip in it you could install a crank winch (like the ones used on small boat trailers for winching the boat onto the trailer) on the opposite side that you would be entering the kayak from. Have the rope from the winch lay under the kayak and fastened to the other side of the slip. Tighten the rope just enough to add stability while entering or exiting the boat. Good stabilty from the rope might be just behind the cockpit. Holding the paddle across the back of the coaming would also add some balance while entering or exiting. Once your in the kayak just uncrank the rope and off you go. When you come back in position the rope and crank it back up. You might have to add some weight to the rope so it sinks below the hull. As for a canoe you might want two winches installed near the seats. Good luck.