Hey Auntjemimma,
clamps for such an application are usually strong beams that go over and under the sheets and that surpass the entire width and are clamped together at the ends. You would need a number of them.
But instead of using clamps at all, you could use one or two hundred short chipboard screws. I would pre-drill and pre-countersink holes. I have already glued plywood boards this way.
As Tom @TMToronto mentioned, a thin and even layer of glue is important.
Alternatively you could also use the screws and omit the glueing step.
For ensuring that the sheets are not in a twisted position you could use some long aluminium profiles as winding sticks. They would have to be longer than the sheet’s width and regarding the length of the sheet, I would check twisting at multiple positions in intervals.
But first of all you would need a support. Do you have two, better three very long, reliably straight beams? Maybe steel profiles? If yes, the next step would be to put them in parallel positions and level them so that they are coplanar. And to fix them somehow.
Then you would have a support for the glueing step.
Or you ask around among friends whether someone has something like this and can lend it to you:
PeFi, Public domain, via Wikimedia Commons
