@Borat Sister,
Borat Sister wrote:
You must have a bladder of steel!
Ha! Not nearly as bad as I guess I made it out to be.
My routine if I have to stop at the Aduana (or even if I don't if I have up to date paperwork) is to stop at Exit 13 on the American side. That's 13 miles from the border. There I'll gas up, get something to eat and drink for the road, go to the bathroom, etc.
My exit in Austin is 232, so that many miles. I-35 that runs through Austin, slams right into Mexico, the zero mile.
More than 1/2 the time the wait at the Aduana isn't that bad, an hour or 2 total. If you have your paperwork in order you don't even need to stop.
You need that paperwork because about 15 miles in is a check point. You're going from the free zone to the zone where you need a visa to travel. Sometimes you're asked to show your papers, sometimes you're not. But if you're asked and you don't have them, you'll have to go back to the US.
I don't like to stop for anything in Nuevo Laredo to be honest. It's not that safe. You want to cross over in the daylight, and get on the freeway and go.
After you're on the freeway, there's modern service centers at regular intervals.
So, there's enough opportunity to pee. I just don't overindulge in beverages that day.
There's a large complex/service plaza Parador Turístico San Pedro that's almost exactly half way between Nuevo Laredo and San Miguel. So that's my scheduled pit stop to gas up again, and get a snack and pee.