Are you checking for ketones?
And, if you were home to monitor, I think you could make a tiny increase (0.1) in the daytime insulin dose when she pre-tests around 300, and when you are available to monitor.
When she pre-tests around 300, and gets 1.0 unit, the lowest Cassie has gone is 78
When she pre-tests around 200, and gets 1.0 unit, the lowest Cassie has gone is 49, so 1.0 unit may be a bit much then. Perhaps that would be a time to reduce to 0.8.