Some tidying up and some progress.
Thomas sent me some splendid thoughts including this: "I think the answer lies in a reworking of the relationship between the pocket to the overall garment. Some sort of integrated pouch system more than a pocket, cleverly attached and of a stiff enough fabric so the pocket doesn't sag." He's right. Good to see I'm not alone in worrying about this.
And Richard sent me a link which exactly answered one of my questions: exactly. Medieval Futures: Attitudes To The Future In The Middle Ages.
And I have a first line. Once I have a first line I'm happy. First line:
This is just a lie.