Displaying both Target End and Due Date on Portfolio chart

[Paul Evans]

I would like to show the distinction between Target End date and the Due Date in Portfolio.  My organization is driven by Due Dates, but to plan the team's time effectively, we will want to target early completion.  I know I can change the end of the bar to be Due Date vice Target End and I know how to show the due date as a data field, however, I would like to display both in the Gantt chart.

I think the ideal display would be to use Target Start and Target End for the bar, then use Due Date to put a Diamond or other milestone-like symbol on the bar to show the slack time between when we expect to be done vs the externally required due date.