Your setup is very very similar to mine... so I am following this with keen interest. While Beneteau may have the "ideal design", that design of course is on their boats, not on the Classic Plastic that may of us are sailing.

I have more hull contact for my CP than you appear to have, but then I have a hull bump and rail bump that the chainplates also rest on. There is a solid backing plate behind the plates.

So what I am hearing here is that one should if possible increase the thickness of the CP and have them mirror polished, to ensure long life.