My wife bought the hinged ladder from West Marine and it has worked very well. There are 2 mounting fixtures that I attached to the gunnel. They are very secure so that the ladder feels like a permanent fixture, but it is easily removed. My stern also slopes inward so the ladder does not hang straight down. I cut the aluminum stand-off feet as short as I could so the ladder clears the bottom of the stern, but it is still angled slightly. This does cause a problem because the flimsy rubber gaskets that are supplied will disintegrate easily, especially with the leverage when standing on the bottom rung. However, I was able to find a very hard plastic gasket that with a little trimming, fits inside the stainless steel tubes and provides a very secure fitting so that the tubes do not pinch together when the ladder is deployed. I have only needed to replace them once in 5 years and they are still in great shape now. We use our ladder a lot because we do a lot of swimming off the boat. The dog even climbs up the ladder on her own.
We have 3 rungs in the water (3 in and 3 out if I'm not mistaken). For us, not having a solid ladder would be a big problem. Ours has worked perfectly well and we have not had to go to the expense of a custom fit so we are very satisfied.
The hinge is basically at the waterline, so when healed, a corner of the ladder at the hinge causes some turbulence at the stern. If we raced, I would remove the ladder for a cleaner line.
With the hinge at the waterline, I can pull the ladder down when I am in the water easily without the use of a rope. However, when I am in the boat, I have to reach down to the waterline to pull the end up out of the water. This could be done much more easily if I fixed a rope for hauling the ladder up, but I haven't done that yet.
