Agreed, nsr. I forgot to add the obvious. If you are driving a vehicle with a US plate and have a US-issued driver license on I-8/I-10, do NOT tell these HSO’s that your destination is Nogales, Agua Prieta, Juarez, Nuevo Laredo, etc. Even if it is, keep the conversation simple (and north of the US/MX border) and tell them, “El Paso” or “Austin.”
Have your answers figured out before you leave for your trip.
This will save you all kinds of headaches and keep your trunk from being opened and rifled thru.