Believe it or not, I have “arm chair” planned this route dozens of times. One of my life goals is to fly a single engine plane around the world.
I would fly the Japan to Alaska route as follows:
RJCC CHE V6 OBE OTR1 NANNO POXED A590 POWAL R591 SYA PASY
PASY is a US Air Force base and you’d have to get special permission to land there, but I understand that is possible. Since PASY does not have 100LL, you’d need to get at least one 55 gallon drum of 100LL sent there beforehand which would probably be the bigger challenge.
This is 1583 NM and would require 8:02 and 142 gals of fuel in a TN22 at FL190 in zero wind according to my FlightStar model. During the summer, you’d normally have a good tailwind, but I’d plan my fuel on zero wind. As Mike Busch says, you’d need a ferry tank installed. This route keeps you out of Russian airspace which is important. Flying IFR through Russian airspace is a huge hassle as I understand it. There are some airways that are closer to shore (but still outside Russian airspace), but they are charted as one-way to the southeast. You might be able to get permission to use them in the wrong direction since you will be well below the airliners, but I’d flight plan for A590.
I’d file PADK (343 NM from PASY) as my alternate (1300-3 or 1600-2 alternate minimums) and have enough fuel to hold there for at least two hours. PASY-PADK requires 33 gals and 1:52 in zero wind. So, using 14gph at two hours for the reserve, you’d need a total of 203 gallons or 111 gals (670 lbs) in the ferry tank. With two 170 lbs pilots, 100 lbs for a raft, charts, and other emergency equipment, you’d probably weigh about 4,100lbs or 21% over gross. As Mike also mentioned, it is fairly common for the FAA to issue ferry permits at this sort of weight so long as the CG is well centered.
Assuming you land at PASY (i.e., you don’t have to go to the alternate), you should have about 71 gals remaining. Adding 55 gals from your pre-shipped drum brings you to 126 gals which is enough fly PASY -> PADU (with plenty of reserves) where 100LL is available.
So, no big deal!
For extra credit: True or False, PASY is the easternmost airport in the United States?