I tuck the "flap" in between the seat and the panel behind it. It stays in place when driving the car and does not flap around or come out.
Marc,
I looked at my 'vert yesterday when I put the boot on for the first time this year. (hey, winter only ended on Thursday up here).
Anyhow, I specifically looked at trying to tuck the boot behind the seat and in front of the metal panel like you mention. On my car, there is absolutely no way to even get a fingernail between those. How in the world did you get that flap in there on your car? The back seat sits flush and firm along the top frame, and very tight to the metal divider frame.
I see no way to acomplish what you show in your picture. Can any other 'vert owners chime in with their results? I would love to see the flap tucked in there, I just see no way it works on my cars.
I would think on cars with the fold down seat option it would work good. But my car has a standard rear seat.