Do you have a spare bedroom, guest room, sewing room that could be converted in to a doggie den? If so, strip the room bare, perhaps even put something along the walls to protect them (plywood). Buy puzzle feeders (we love the buster cube) and some other toys for her. Only leave 1 or 2 out a day and rotate them regularly. This should help provide something for her to do while you're away.
I'll resist going all NLP here (I'm in a mood) and leave it at: if your lifestyle isn't right for a high energy dog likes a GSD, what makes it right for you?