FWIW mine is 57mm, but I thought that would not be reliable across builds which is why I went to axle centre-line. I took a straight piece of metal and laid it on the chainstay, and marked the centre of axle off on it, then measured that. There could be 1-2mm error due to parallax.
That sounds consistent with the impression given by your pic, that your rear frame has an extra 4mm or so clearance which indeed ought to be enough for a scorcher to fit. You may have trouble with the bolt that affixes the mudguard flap, when I was looking into this it appeared that may be an issue.