Thanks for sharing this idea Matt. I can see how a report that shows requests submitted after normal business hours, would help you make the case for staffing off shifts.
Have you tried grouping work orders by the Submittal Date (which also includes a time stamp). I was able to use the Group function in an Excel Pivot Chart to group work orders by the hour of day when they were submitted.
Another option right now would be to use your Custom Category as a drop down for "on" and "off" shifts.
Let me know if you'd like help with either of these options.