Don't support their businesses. Don't let them have domains or websites. Kick them off Google platforms, Facebook, even OKCupid. All private companies need to take action now and make sure none of them can use the internet to spread their hate, or really use any service.
I think it is time to organize contacting car dealerships working next to deny selling any automobiles to them. Eventually we can get the DMV to deny licenses to these dangerous individuals, or at least put them on a registry so the feds can check in on them.