I have always used the Ho Chi Min trail stragety as the US also. It takes a little longer to get things going but having a solid wall of troops cycling through the continent is a deterent. And even if Japan still decides to attack and takes that territory, the US will have a force to be delt with in adjacent territories.
As Japan I think you would have better luck focusing mostly on mainland Asia and as a secondary objective running scrimishes on places like Alaska, Hawaii, New Zeland, Aus., and Brazil.
Taking these places under a scrimish mindset means you are trying to defelect US troops from going to Europe. They will take back those territories and some times very quickly. Don’t take them with the intention of holding them because you have far more to loose in this situation because you have to import the fight.