"anorton" fired this volley in
m:

You could try gluing it to a sacrificial board and using a slitting
saw in a mill.

It's 80" long. I don't have a mill with X-travel that long. If I did
that, I'd have to run it through some guides by hand, like ripping on a
table saw.

That last is another suggestion that's been profered. Screw two waste
sheets together clamping (and maybe also gluing) the work between... then
rip it with a brand new carbide blade and slow feed. ??? Of course,
you'd lose the 'clamping' behind the cut; but maybe that's not an issue.

The length, unrolled, is the bugger-bear for handling it flat.

LLoyd