Problem housebreaking Lab

Question
We recently adopted a 2yr old Lab/Weimeraner mix from a rescue. Beautiful loving dog. Great with the kids. His 'den' is our kitchen along with our golden. When we leave him alone, he jumps the gate and soils the house in various places, even going as far as trying to get out of open windows and destroying the screens. I moved him to a large metal crate when we were gone. He flips this crate over, and squeezes thru the bottom bars, then wanders thru the house soiling it with both urine and feces. So, we went and purchased a heavy plastic crate. yesterday he was in there for just about an hour and he had chewed the plastic to the point where his gums and nose were covered in blood and the bars on the crate are broken thru. He did not manage to get out and soil the house this time, but he did hurt himself. Like I said earlier, he is a wonderful dog. His temperment is perfect and loves our children, but his anxiety when left alone is destroying our home. He is not technically alone as he has our golden by his side, but that does not seem to be enough for him. Please, can you give me some ideas or tips on how to correct this behaviour? We take him out to use the yard as his bathroom before we leave him alone, so I know it is not teh fact that he just has to go. It seems more out of spite or anxiety since we are not home with him.
Any ideas would be greatly appreciated as we really want him to remain a part of our family, but we cannot afford to be replacing the carpeting all thru the house.

Answer
There are so many nice dogs needing homes.  Too bad so many of them come with baggage from their previous life.  I am a strong believer in using a crate.  In this case, it is possible he was abused by being left shut up too long.  Perhaps try a tie down, a short length of chain secured at one end and a snap.  You may also need anti anxiety medication from the vet for a while.  

Long term, work on leadership.  The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm