Off the top of my head, any wadding could/will stick in the baffle stack. I'm not sure on the pressure factor, either. Any can is going to have to be pretty large/heavy to contain the blast, and it would be a challenge to suppress something with a bore size that large.
What HAS been done, however, is to get a very long (backbored?) aluminum bbl assembly for the shotgun, say an extra six feet or so. It's aluminum, so it's not unmanagable.
I saw this in an American Hunter not too long ago. Ypu might try to research it.