A journalist friend of mine was moving to Mexico and had a lot of stuff, including a desktop computer. The customs inspector wanted to do his job, but he was a practical man. Be honest and friendly and things will work out. Be arrogant and you will have trouble. Allow at least 30 minutes for customs clearing.
Weekends are the worst time, especially holidays.
If you got a late start, please spend the night in Reynosa or McAllen. Don't drive at night. You can't see a black cow at night and we haven't seen one yet with tail lights. Book your room online. We respect your privacy.