So that's M12 into 10mm thick aluminium? Do you machine the uneven rear face of the caliper around the fluid port to get it to seal properly with the copper banjo washers and I assume you'll need to strip and clean/air blast the calipers to clear the swarf from re-tapping the fluid port out of the fluid channels? What did you machine the spigot rings for the discs out of?
He's going to get hounded for months - if he ever wanted to spend a year packpacking across somewhere remote I would suggest now is going to be the time!!!!