There are a couple of parking lots to the right as soon as you get through customs.
One behind the Jack in the Box and two or three along beside that one.
I was in Mexico last weekend....I didnt buy anything but I look extremely conspicuous even with my sweatshirt on. Even though I was clean I still get nervous crossing the border. The customs official simply asked if I was bringing anything back, I said no and I walked through.
Bringing gear or anything over the border is extremely risky...sure you may make it through but if you dont....its a felony on your record. Is it worth the risk?