Top three are in my view Idaho, Montana and Wyoming - high dissident population already, few Jews, huge territory, stunning nature, less urbanized.

Next I'd say NH and Maine - they are basically swing states now and even a small influx could have tremendous political influence both on the local and on the federal level. All the dissident right has to do is take over the Republican side of the spectrum, you probably need less than 20% of the population to do that. A dedicated minority of 10-15% white nationalists would radically change local culture and winning republican primaries would be easy.

I'd exclude Delaware and also Rhode Island from the list - too many blacks (Delaware) and Jews (Rhode Island) and also too small territories with a high rate of urbanization.