Hello Iain,
No, this has not been made before, but it should be possible to quickly create them yourself.
You can use these dimensions of the demo PCB in your drawing: 35.1 x 52.1 x 7.2 mm.
If you remove the JTAG connector, the maximum height is reduced to 5.2 mm; if you also remove the coin cell battery (e.g. for passive operation), the maximum height becomes 3.8 mm. Be careful with this, though, as you then also risk to inadvertently push the WAKEUP or the RESET button.
Best,
Dries.