The wheelstand pro guys make an awesome product. I've got a wheelstand pro for my G27, it's just great! Sits steadily on the floor even during heated races
If you haven't already got the wheelstand yet. In answer to the question of how thick the plate is, it's not very.
The clamps on the DFGT don't actually tighten up that far, so what I did was got a bit of wood (probably about an inch or so thick) and use that to clamp between the metal plate and the clamps of the wheel.
Pretty rock solid except I think I've had to slide things back into place and tighten things up again only a couple of times in a couple of years.
If you haven't got it yet and are still thinking about it, do it. Great stand for that wheel, the pedals clamp down nice with the metal bars and everything works superbly together.