I think the real problem with the floating bridge is that it doesn’t really contain Japan.
Well that is true because the Pacific war is at first a naval war. Europe is not like that and Navy does not play a big role besides protecting TRS to shuck troops onto the mainland.
Over in the Pacific you have to get rid of the IJN first and foremost. The land units are just there to take advantage of openings to take Islands and move closer to the main land. Considering how most players play Japan by never reinforcing any of the islands with any size of force. The USA can have 3TRS with 6 guys and do some serious IPC harm on Japan and their islands. It does not require a huge TRS fleet in the Pacific until late game.
Now lets look at the 18 TRS shuck to the Philippines. So you are sending 12 troops a turn to Manila. So, you wait one turn, now you have 12 TRS sitting in Manila with 24 Units, and you can threaten the entire mainland of China, from Singapore to Tokyo. Since you broke the shuck you then have 2 turns later another 12 units come from Hawaii to reinforce.
IMO the fastest way to neutralize Japan is to kill their IPC economy and that is found in the South Pacific and the coast of China. I understand the idea of going north but I do not think that is the best way to take down Japan. Taking Korea and all that stuff is end game moves for the USA to finally knock out Japan on their main island.
My question for you is at what turn do you think you will have enough of a US Navy to be able to build 18 transports and the support ships to protect the trns and to wipe out the Japan Navy?
By that time, Japan will be deep into China and maybe Russia. They will probably have India too. If such is the case, they can relax and start building naval units to counter yours. Unless you are severely ignoring Europe, it is very possible to never be able to get that deep into Japanese waters safely with so many IPCs being spent on Transports.