What you have to gain (or the tenant's future electrical worker has to gain) is nothing more than knowing whether a given outlet is powered by your phase A or one of the other two. But they won't need to know that while standing at the outlet. They can learn that when they go to the panel to turn off the circuit. There is nothing to gain by adding phase taping.
Now let's get down to the real issue. The inspectors are wrong in saying that the word "premises" is the sticking point. The rule does not use that word in isolation. Rather, it uses the three word phrase, "premises wiring system." That phrase has a definition in article 100. Here, then, is the critical question: does the utility provide a separate meter just upstream of your 120/208V panel? Put another way, is your panel a "service panel"? If so, then article 100 would tell us that your tenant space has its own "premises wiring system," because that phrase starts at the service and ends at the outlet. Therefore, your premises wiring system (i.e., your tenant's space and no other tenant's space at the mall) does not have branch circuit wiring from more than one nominal voltage system. QED
(Aside: Sadly, if you were to tell us that the utility provides its service to a central electrical room elsewhere in the mall, and that your panel gets power from a feeder and not from a service, I would have to side with the inspectors.)