I would be teaching her the door. Associate the door of course with going outside. When you go to the door use the 'bathroom' word in a very happy upbeat tone. If she has a favourite toy - entice her this way as well.
I would use the crate but not too frequently until she understands the door. I would take her out in the morning (as close to your work schedule as possible), then put her into her crate after you have come back. Go through your morning routine while she is in the crate: shower, breakfast etc. Then take her out of the crate, put her on the leash and take her out again.
Throughout the day I would umbilical train her (yes leash around your waist) and take her out again at lunch hour and then the same time you would expect to come home from work. Again at night before bed.
Routine usually works well.
(PS - I tried the diaper thing - it did not work as I was desperate to entertained the thought for one of my fosters).