OK, what in the world have I done wrong?!? The sheet is "the right size" but the carcass does have a bit of flex in it (seems a few mm wider at the front than the back, although lockdown bar fits just fine).

I've got the side receiving channels and it BARELY hold the back. Interesting side note I noticed the rear receiving channel is only 58cm wide.

Guess I'll just need to get another one cut at 614mm.

Anybody in Melbourne want a sheet of toughened WideBody glass for $50?