Looking for a hard backpack case for my classical guitar. Help?

Hi guys. I recently acquired a lovely Rainsong guitar and it has a great hard case. But as I'm a music therapist I'm usually lugging around a LOT of different instruments and it'd be great if I could strap my guitar to my back. I've been looking for a backpack case but they're all soft gig-bag types and I'd like something with a bit more safety. Any suggestions? Thanks!