While you're home this evening, maybe try Angus and Roxey in a room by themselves for just 30 minutes. Then tomorrow try them in the same room for an hour or more. Just test them out to see if they stay in there and don't tear up anything. You can gradually increase the time until you feel comfortable that you can leave them in the room for the whole work day.

If it comes down to it, I would crate her and not tie her in the yard. I'd be terrified she might choke herself or get into some sort of trouble on a tie down.