A crate sounds like your only option. My two GSD's can not be left loose in the house for more than an hour. They have chewed up couches, blankets, remote's, cell phones, cordless phones, pillows... etc.. (I could go on! )

I have to put them in crates, they love them!! It's "Their Safe House" My Buddy will go in his even when we are home. He's afraid of thunder and when it storms, that's where he goes! I leave a radio on for them all the time too.
Orrrr... sounds like your pup could use a friend!! Sierra was VERY bad (breaking out of crates) before we got Buddy, once we adopted Buddy, she's a happy happy girl!