As someone who is often sitting in one of those cars behind you in such situations
I still say NO to a search when I get stopped. (and no, I don't suggest flashing credentials)
A friend and I were stopped near a major city where an interdiction operation was obviously underway. We were in a small sports car travelling back from a long trip after taking a look at an airplane he was looking at buying. We had no luggage, coolers, etc... the stuff you would normally see people take on a road trip. They questioned us extensively and we denied the search. We were in a hurry to get home and didn't have time to dick with it.
I see no problem denying the search. It's your right.
I'm always amazed at the fools with something to actually hide that do say ok and end up in jail.
RF addict