After a long test test I can say that this is the way to go. Most numbers have been tweaked so that it would result in 15-20% lower pressure.
For mostly highway driving the fuel consumption is now down to
I don't have any numbers yet on city / heavy traffic consumption, it might be a different story.
I don't know the long-term effects on neither reliability nor pollution, the injector nozzle spray pattern might not be suitable for such low pressures.
Edit: article was amended after I discovered some miscalculations. I forgot to take into account a mid-trip refueling. New calculation falls within statistical error. This project seems like a fail.