Foil plate adapter

I got a kanaha shapes board that uses 5/16 screw and my mast uses m6 screw. I dont want to mess up the mast by making the holes bigger to accomodate the 5/16 screws. I’m looking for making similar plate adapter as F-one 4 point mount plate. Has anyone done it? Can you share the cnc file ? Thanks

Maybe there are helicoils you could use to get to m6 or 1/4 that would work