Well, it works in principle
I'll have to play with the tolerances around the T-slot part (it was too narrow and I had to expand it to get it to slot in) but once the holder is in place, it's stiff to move it around, and it's rock-solid when trying to pull it off.
Mesh ought to arrive "tonight by 10pm" [aside: that's *really* stretching 'next-day delivery' guys] so I'll see how it works with the mesh probably tomorrow.