Hooray! I did it!
But who's wearing the first completed Metropole in a Sidewind sock? Yup - my son!
The gauge issue resulted in a much wider sock than planned and my son claimed it.
The construction method at least meant I could adjust the foot and toe length at the last minute.
The final stages were straightforward. I used garter stitch at the back of the leg as suggested by the Sidewinder pattern for a little bit of "grip". Then it was a case of a long, long kitchener graft down the back of the leg and along the foot, to make a tube of fabric with a 90 degree turn at the heel.
Then I used smaller dpns (2.5mm instead of 2.75mm) to pick up stitches round the top for the cuff and the bottom for the toe. This should make the cuff slightly tighter to hold it up, and the toe more densely knitted, so stronger.
Verdict? A success as far as my son is concerned! But they were far too wide for anyone else in the family. But now that I understand the method, I am confident about making another smaller pair for my daughter.
Now I just need to decipher my notations to make the second sock to match!