Conditional Formatting (or custom icons) on Timesheet Entry Grid

I need a mechanism to *easily* review custom fields on timesheet records.  I think conditional formatting of the entry grid (matrix) is the best approach.

Use Case: We have a toggle for "On-Site" and I require an approver to know what he/she is approving.  The only 3 ways to review (that I've determined) are: 1.) clicking into each cell, 2.) running a report or 3.) creating separate Team Views for either state of the On-site toggle.  

Suffice it to say, my users are unhappy with any of these options.

My feature request is the ability to add conditional formatting to the time entry matrix highlighting certain states of the toggle.  Alternatively, adding additional custom icons (such as the gray/green check and comment's note) may work better.