As for your points... The Japanese invaded a few remote islands in the Aleutians which amounted to nothing; the resources were better spent further south. Any invasion would require an even more successful Japan, and the probability of Japan doing even better in WW2, much less winning, has been argued in other threads many times over. Pearl Harbor itself was another massive gamble. The prospects of an invasion of the Hawaiian islands are just as farfetched as Alaska in WW2.
I still like the suggestion of evacuating Alaska, letting the Japanese have it. By the time the Japanese are able to complete the equivalent to the Alcan Highway from North end in order to invade the Contiguous US (Lower 48), it will be the grandchildren of the original solders, and they will all speak English.