http://www.katoby.com/Products/Soothsoft/CanineCooler/
Pet Value in Ontario sometimes carries these, in summer. They do work, I ordered a small human pillow sized one for myself, from a pharmacy. I would worry about toenail punctures and they are not to be used for dogs who will chew and bite their bedding. You might be able to order one at a human pharmacy too.
I have also heard of people buying thick rubber matting that is used in cow barns for the cows to lie on. You will have to check out some farm supply stores but I think this has been used for chewers who will eat their bedding. Fit inside the metal tray of the crate is important, must not be any gaps where dog could get an edge up. Sorry, I don't know the proper name of these.
I also cringe when I hear the poor dog is in a crate for so long. I expect the chewing and bad behaviour is boredom. Could you build a pen in a little used room for her? We did that when our first girl was a puppy.