To the posters suggesting this wouldn't work for Evangelicals, I absolutely agree. It's groups like Ultra-Orthodox Jews, orthodox Calvinists, Mormons that would be able to make this plan work. Evangelicals by their very nature aren't inclined to separate and their church structure would make it very difficult to do so even if they were inclined to be.
Not by their nature as Evangelicals - by their nature as part and parcel of American mainstream culture. To become a well-organized minority group with considerable minority influence, you'll first need to
be a minority community, divorced from the majority culture.