I worried about the same thing, but saw so many pix and no comments about chewing the coroplast, so away I went. However!!! Today I saw at least three spots where my piglets have been chewing after only a week in their new cage. I too, have plenty of other chewing items available to them, so that is not the problem. I am going to check out the report binders, that is a great idea and here's hoping that they won't be able to get a grip on the edges of the binders and chew them up.
As for plastic making them sick, on one occasion I lost my tupperware scoop that I used for their pellets and didn't have a clue what happened to it until cage cleaning day when I found bits and pieces of plastic all through their bedding. CSI could have had a field day with the evidence! In any case, they seemed to have survived it and it has been over a month ago it happened. I am, of course, being more careful as to what comes in their reach.
Thanks,
Michelle