My Mylee is the exact same way. She has severe separation anxiety. I have used the xpen (she climbed out), a travel crate (she barked and panted till she was soaked from her own saliva), and a large wire crate (she did the same as you describe). Nothing has worked, so we've been leaving her out and she has done fine this way. I know you say this is not an option for you, but would it be if you could puppy proof or block access to certain rooms? Mylee only gets the living room and hallway while I am gone. No bedrooms or basement. This has worked well for us even with her being on a limited exercise program because of leg issues. Since my expensive xpen was a failure, I use sections of it to block off my furniture and keep her from jumping....it has been great that way
. I have found too with Mylee, that consistancy is necessary. She freaks if I do something out of order. Good luck.