The boot floor - or rather spare wheel well covers - on my old Rover are made of plywood. The front has a steel lip which rests on the top of the well with a hasp under it which fits in a rubber thingie, so it can move neither up or down. The rear sits on a cross section running across the rear of the car and is secured with a turnbuckle. The whole lot covered with a carpet. Some time back after a accident, the rear panel was replaced, and it didn't have the turnbuckle fixing. But where it should be, a plain thread.
So what would be the best fixing to hold the floor securely - one which can be easily undone by hand. As the tools live beneath this floor...
Needs to be flush too so as not to show through the carpet.