Ed's trip involved a Necky Tofino, with 2 cockpits, as shown in the pic of him departing monterey, not modified to put him in the center, as was stated by someone herein. I've used the Katadyn R/O filter extensively and successfully in desert environments over the last 10 years, and have no complaints, but I strongly recommend that you carry 2 of them, plus 2 full rebuild kits, and carry 2 spare filter membranes. Failure of this system would mean you die, so be very savvy about it, unlike a certain famous female rower who didn't know how to fix hers on her solo row to hawaii a couple summers ago. Lucky for her, she bummed some water off another boat, thus ending her "self supported" status.
I also have considered repeating Ed's trip. It's not one to be taken lightly, and you stand a decent chance of not returning if you choose to play this game. Plenty of people have disappeared doing blue water crossings in kayaks. As for entire oceanic crossings, I'm sure you're aware of Romer's trip back in the 30s. and probably aware of the greenland kayaker who did an unintended big crossing to northern UK in the 1500s. My take on it is that I'll have to do a few longish (100 to 300 mile) blue water crossings before I would even seriously consider the hawaii crossing. And a point to consider seriously; Modern parafoils are about a thousand times more capable of towing you than the old jarlbert kite that Ed used. Take a cue from the kiteboarders. a 5 meter kite should be able to get you a couple hundred miles in a day, if conditions are right. Ed made over 120 miles one day using his 2 meter kite.....but had many days of flatwater paddling in the doldrums too. I wouldn't even consider doing it without multiple sizes of kites, if I expected to arrive in hawaii alive anyways. As for food, I'd be careful of the freeze dried stuff..that stuff is usually too high in sodium. although you CAN make your own freeze drier and prepare whatever you want.
PS: The trip from Japan to Hawaii would be utter goddamned madness. The current would take you through a much rowdier, colder part of the pacific than what Ed did. I suggest you do your homework on this topic alot more in depth, so you don' get yourself killed.. the north pacific is no joke, son.