This looks a good system the pictures are very useful and this is what I need to do to stop damage to cockpit tent fitting getting caught by sheets. I guess I'll just have to start cutting holes to fit the components not, something I was expecting to have to do with a new boat. I agree these fittings should have been in place when genoa tracks and cars specified at build. I guess new boats are built for boat shows.  Many thanks.

The screws are reachable inside the innerliner, by removing the glued wooden innerliner under the deck - in the aft cabin. Using a razor sharp knife, I was able to carefully remove it...

I've used some 13mm water-proof plywood and some 10mm shieves, and lock nut's from the inside. I believe it's M6 acid-proof bolts used for this; the same as the ones used on the cabin roof - but longer.

I had to use two long bolts, with a "combiner" in the middle.  There are no acid-proof bolt long enough in the M8 size available - at least not in Norway.