There's no "honest engineering" that will solve the problem. This is exactly what regulators are for, because there are huge incentives for the executives on both the airline side and the Boeing side to make a deal here... everyone saves money and takes home huge bonuses.
As it is, we have a bunch of regulations, and obviously no greater safety; the planes designs have issues anyway, as they did here with the 737 Max.
There's certainly regulatory capture going on in Boeing too, no doubt, but that's also a point for removing the regulatory system, not a point for 'making it better', usually by adding more rules, seldom subtracting rules.
There very much is: tell the customers that changing aerodynamics means changing the plane. Full stop.