Going the bid route, I think I agree with your assessment. It’s a little scary still that if USA doesn’t attack canada, they are in deep trouble. The attack’s odds aren’t exactly without some nail-biting for the US, but it does help.
But like Larry once said, he hates bids, so there are other solutions that I think we should consider. As much as sealion got nerfed from A2 to A3, it would not surprise me if Larry was interested in making this not even a realistic option for Japan, instead of changing it from slam-dunk to ill-advised.
With Russia you touch on why I think pac is played so little by itself. In Global. Japan has to choose to go after Russia or not. US has to balance Atlantic and Pacific purchases. UK has to decide whether anything from India needs to go to Egypt or vice-versa. In just Pacific, there aren’t really many decisions. That’s not really a ton of fun.
Regardless, going the bid route, if the non-USA allies also need help, a bid nearing/exceeding 20 is hardly unreasonable, especially if USA’s only hope with the 12 bid is a 65% attack. IMO Japan having easily an easily 75+% chance of taking USA is far too much when USA has no choice in the matter, USA having a much stronger chance than 65% on the Canada attack is OK because Japan has the choice of not putting itself in that position. I think I wrote that sensically, let me know if not.