The plate is rated for a max temperature of 572°F (300°C) so I was hoping that a heat gun and thin putty knife would make separating easy without affecting the temper much. But the adhesive information only states "heat resistant." Is this asking for trouble?
Edit: Why I don't want to use clamps - the sandwich is too large to be mill-drilled all at once, so it must be repositioned. The holes must be at (close as possible) right angles to each other, so the pieces cannot shift while moved and re-indexed.