This would be remarkably easy to prevent with a simple relay that switches fron ‘on’ to ‘off’ when energized, placed from the alternator output to frame ground.
This would automatically ‘ground’ both sides of the diode when the engine is not running.
How you do that when you are driving the vehicle and both sides can't be grounded? I can think of a way or two, but that's a more difficult problem.
We're facing the same kind of thing with the power infrastructure. There are ways to prevent the damage, but it's gonna cost money and require work.
/johnny