Thanks, Mark! A few photos would be nice, especially, the thumb-screws. I assumed there are no tracks in the floor and the screws are fixed in place. Just the slotted plates. We did get a price from Selene Americas of $175 plus shipping from China for the hardware, but we're trying to get out of the yard soon, so delivery time is not ideal. Hence, seeing if we can fabricate something at a reasonable price.
Nick