The trouble with my dog

Many of you may know that I have two dogs. One of these dogs is Penny. I adopted Penny from the pound in September. Penny is a lab cross - we are not sure what she is crossed with, but I am leaning towards moose!
You may be wondering why I am talking about Penny. That would be because Penny has separation anxiety. Now unlike when we leave Brindie (my other dog), when we leave Penny things aren't the same when we return. Penny has eaten through everything from food to rocks and foot stools. She does not adjust well to being alone.
When you are with Penny she is calm and well behaved but in today's society it is impossible to be with your dog all of the time. Although Penny is never really alone, Brindie is always with her; we had to wean her from human company.
First we thought we would try kenneling her. I first sat in the kennel with her, then I went right outside the kennel. Eventually I got to the point where I was upstairs making no noise with her downstairs. I could do this for quite a while, so I started leaving her in the kennel. This was all good until one day when she ate the plastic flooring of the kennel. So I took out the flooring leaving her there with just the bars under her, believing she couldn't eat through metal.
Of course I was wrong. I got home to discover not only had she bent back the metal bars, she had also eaten and shredded her way through the carpet all the way to the wood paneling under that. Now the carpet was one of the ugly basement carpets that cover our basement, but that is not to say that my parents were too pleased. We agreed that something had to be done and fast.
Now getting rid of her was not an option because giving up doesn't solve anything and I knew no one else would take her. So we started taking her for longer walks and we even bought a doggy backpack. Now she does look a little weird in it as we put weights in either side to wear her down. I was tempted to put treats in it and watch her chase herself but I figured she would eventually destroy it.
I am glad to say, no matter how weird I look walking down the street with two dogs strapped to me and one with a backpack strapped to it, Penny hasn't destroyed anything for a month. A month may not seem long, but in dog time She hasn't been destroying stuff for quite awhile.