I honestly wouldn't have a problem with a white ethnostate existing somewhere in the world. Make sure they have arable land and access to the sea and just let them do their thing.

Other countries can be free to trade with them or not, they can make their own rules for who to admit to the country, and we just leave them alone. If the country turns to shit, they won't be able to blame anyone else and we can then point to it as an example for future reference. I feel like somewhere in the United States is the most suitable because the entire country was stolen from natives anyway and there's a big concentration of white supremacists here already.