Of course there is nothing new under the sun. Looking on the RMweb community and N-gauge forum, I find that people have been making their own transparent Rapido couplers, and that Mathieson fit their PO wagons with them, and offer spares. I think you will agree that transparency makes the couplers a lot less conspicuous?
And after my comments on 3-link coupling, I find that these are also available from Mathiesons. They are semi-permanent, so no auto-uncoupling is possible, but there is potential here for us in permanently coupled sets of stock.