There's been a few mentions of capturing Marcus Island (Minamitorishima) in WWII to bring Japan within range of US bombers early in the war. What if the US decides to go on the defensive in the Southwest Pacific and instead focus on taking Marcus Island? If the island is seized after Midway, it would bring Japan into bomber range two years early. The island could also be used as a stepping stone to Iwo Jima, which could be used as a stepping stone to Japan proper.
So my questions are:
1) How early could Marcus Island be captured?
2) How would the Allies keep the shipping lanes to Australia open without the offensive in the Solomons?
3) Is Marcus Island a realistic jumping-off point for the Central Pacific Offensive?
4) Should Wake Island be captured before Marcus Island to provide land-based air support?