Seperation Anxiety - Please Help, What more can I do?

Question
I have a 5 month old male yellow lab. He has completed puppy school and is now doing a basic manners course. He is very intelligent and learns quickly but is very stubborn.
We crated him from the start with no problems, he is still sleeping in the crate in our laundry at night (with no problem). I work an hour in the morning and an hour in the afternoon but my lab hates being left alone (either in the laundry or in the backyard). He looks sad when I leave and understand when I say I will be back. I leave him toys, a bone, a stuffed Kong, treats buried in his sandpit, water and a warm kennel but nothing is touched when I get back (he starts playing with these things once I get back).
The problem is when I come back he barks, jumps on me, nips & tears my clothes and will not let me out of his sight. Everything he seems to have learnt seems to be forgotten, it almost feels like he is punishing me for leaving. I have tried ignoring him till he calms down, not making  a fuss on departure or arrival. Nothing seems to work. Even if he has been walked and is tired, this does not help. He is not scared of the yard, he plays out there often (though I have trouble getting him to play out there while I am inside).I know labs tend to suffer from anxiety but he is never left alone for more then a couple of hours a day & when my husband or I are home he gets lots of playtime & exercise.

Answer
Try leaving him in his crate.  Leaving him in the laundry or backyard means he is in charge of it.  Perhaps too much responsibility.  

Also try making a big fuss over him when you return.  I know the ignore is common advice, but I wonder how much science is behind it or is it just somebody's theory.  I always let my puppies know i am happy to be back.  They don't have to jump up on me to get attention.