Chewing up pee pad

Question
Hi, I have a 4 month old Cockapoo/Lhasa Apso mix.  He's quite intelligent, and picks things up very quickly.  One of these things is using his pad to do his business, he is also starting to learn how to hold it till I can take him outside (though at this point not very long).

During the day when I'm at work, he's in his pen.  Enough room that on one side is his pee pad, and the other half for him to play and sleep.  Although I leave chew toys for him, there have been times (not all the time) that I come home and he has chewed up his pee pad to shreds.  Stuffing everywhere, including in his hair.  And some of those times, he has already used the pad.  So his "stuff" ends up kinda everywhere too.  The other problem is because when he does chew up his pad, he's got no where to go.  Except, you guessed it, the floor.

He doesn't do this when I'm around, so it's almost impossible to correct him.  I've heard spraying the pad with bitter apple has helped some people.  But I've also heard that this can deter dogs from using the pad (can you confirm this?).  I've also read that this could be because he's bored or frustrated, because of pent up energy.  I walk him for about 20 - 30 min before I go to work.  I walk him for about an hour when I get home (though not consistently, as there are those one or two days that I don't have time or the weather is bad).  But he does get moderate excercise.

Is there a way of keeping him from chewing his pads?  Any suggestion is greatly appreciated.

Thanks in advance.

Answer
Eric-

Pee Pads seem to be a very popular puppy chew toy :)

Have you tried pee pad frames? http://www.valleyvet.com/ct_detail.html?PGGUID=63F97E8A-E98C-4A7F-8642-5B108C135...

I have never used them, since I do not normally use pee pads, but I have heard they work wonders since they were specifically designed for the chewers.

I hope it helps! Good luck!