I'd have finished.
Two thoughts I would have: grass packed in the tyre to get to checkpoint, then find a town or someone at checkpoint and beg, borrow a 700 wheel of any kind. Are they dumb thoughts? (yes probably).
Not dumb thoughts, but missing the obvious: Sausages in tire, ride on, find tube, eat sausages, win.
@Squaredisk started
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I'd have finished.