I will even pay for Eric's dinner. I will be there from Sept 22-28 in Tyson's Corner. He can DC Metro on the Silver Line. If he doesn't have an auditor by then, I can make suggestions.
I don't do rental cars in the DC area, I do the DC Metro, tell him to get a DC Metro card and Uber. Don't eat on the train, he will get kicked off. But DC Union has great restaurants. Eat there before transferring.
I think Dulles has Legal Sea Foods outside Security, and has good chowda and lobster.
They also have TSA Pre.