1) There was a feasibility study done prior to the forming of Operation MI, but even at the height of their victory disease the IJN could see that taking Oahu six months after Pearl Harbor was simply beyond their means.
At best, following a successful MI in which the USN gets curbstomped with no loss for the IJN, they could plan a later series of carrier raids with everything they had, to neutralize Pearl without invasion. Assuming the US 7th Air Force by that time wasn't stronger than the entire Kido Butai!
2) Except the whole concept of the attack on Pearl was Yamamoto's brainchild. He was a gambler, but he wasn't a fool. Sending out the Kido Butai from Truk puts it in the shipping lanes, all but insuring exposure and loss of surprise, not to mention going up against an alerted US Pacific Fleet.
Nagumo could face a Battle of Tsushima in reverse!
3) I can't see Yamamoto taking such a risk. Even his planned attack was relatively safe compared to a Truk route.
By those standards of proof, the operators of NTS Newport, their workforce and unions, their Rhode Island congressional supporters, and the entire USN Bureau of Ordnance were Japanese spies and saboteurs!
Yamamoto may have been blind to grand strategy, or even just plain strategy, but he certainly was a man who understood operations. He knew what he was doing with the northerly route. He couldn't have known how far away the carriers were (in fact, only the Enterprise was in range), and the KB did far better both in terms of damage inflicted and scarcity of casualties than he ever expected.
There's this place called the Cape of Good Hope. And Australia. Long LOCs, but convoys could still use Pearl as a depot (and California as the source), while giving MacArthur his dream of having the war against Japan directed from his area.
4) How long will Japanese agents last in a land swarming with US troops, National Guardsmen, and constabulary with both eyes out for anyone even remotely looking Japanese? Remember, the internment camps have already been completed by now, so they can't "disappear" into the Japanese-American population, even if the Nisei let them, which they wouldn't.
5) Logistically impossible, insane LOCs, no bases for operations locally (no safe houses), too much defense, no way to avoid being seen.
6) Ice, clouds, fog, high winds, snow, polar bears. Not a place to make war. At least in Russia they had summer and fall. In the far north they have July & August. Or sometimes just August.
7) Time-time-time-time-time. The Russians will be halfway to Tokyo (and more than a few atomic bombs will be ready) before these routes are ready. Making canals bisecting continents takes a VERY long time.
8) And it'll have to be by the US. As far as Winston Churchill was concerned, the Lands Down Under could go hang. I don't think he ever said that, even in his own most private thoughts. But his policies certainly showed that. No matter what the strategic situation, even if all other situations the UK was responsible for were relatively stable at any given moment, Churchill would always prefer to use fresh forces to build up for new offensives elsewhere, rather than succor Australia and New Zealand in their hour of need.
Rather churlish, considering how much effort the Aussies and Kiwis had exerted on behalf of Britain before Japan's entry.
9) ATL's to the contrary, the only people in Japan who ever proposed an invasion of Australia was the Imperial Japanese Naval General Staff, and only AFTER a successful MI, destruction of the remaining Pacific Fleet, taking Port Moresby, taking Fiji-Samoa, taking Johnston-Palmyra, and raiding Oahu again.
After looking at the projections of what would be needed for such a Napoleonic scale invasion in terms of transports, troops, tanks, artillery, ammunition, fuel, food,
water, (Australia is 70% desert!) and time, the Imperial Japanese
Army General Staff just about had a collective coronary! They argued that such an invasion would cost them a whole year's worth of fighting in China. With the full support of Combined Fleet, the IJA won that argument decisively.