IMO, any strategy or attempt to filter out the "right" candidates can always be gamed that a change of culture is inevitable. Iron Law of Bureaucracy. You can delay it, but it will happen. Just look at Google today despite their massive investments in the hiring process. I think if you really want to preserve your culture long term, you need to start looking to exporting your culture outwards into general society rat…
Given how the culture of every company I've ever worked for was a stinking, nasty, high-school environment and how the companies' values did nothing but encourage ineptitude and mediocrity, I'm glad that companies absolutely suck at exporting their culture as much as they suck at building it. Your suggestion will give me nightmares for weeks.
But my point of how internal culture gradually changes is in effect an exportation from another culture to this one. If the toxic practices you are describing were to begin to become relentlessly exported to the environment around you, remaining defensive dosen't work long term. You'd need to push back.