Um, not quite. A stack of 3/8 washers for the one side is fine but on the other what I'm suggesting is a thick bit of steel with a 5mm hole in it so it jams against the end of the axle and leaves the axle nut and adjuster free to adjust while the skewer is left tight. A little block of 1/8 to 3/16 thick steel with a 13/64 hole would do it nicely.