These are the Mk2 brackets. Still perspex, although I've concluded that 1/4" aluminium would be more durable, and I just happen to have some in the offcuts box, so maybe when I have more time. If these were made from alloy plate, and the stainless angle brackets were productionised, it would make a viable product, maybe with a tinted film.
Here we have the slightly larger bracket, slightly smaller locating hole, and bigger stainless angle bracket.

You can also see the full with neoprene buffer - topside at the front, and underneath at the rear. This also pinches the head restraint stalk and provides a firm location. This neoprene is standard density kneeling mat from 'outdoor/hiking' shops.

The horizontal fasteners have wider spacers and bigger diameter washers to spread the load. (Compare with earlier photos).

You can see here that the IRS0826 neoprene edging, which is round, really adds to the 'product'.........

And on the final photo, you can also see my 'half-half' tonneau which fiils the gap between hood cover and windstop. I'll be getting some edging fitted to this as a final touch.