If passing as a "tourist" make sure you are ready to answer "no
" if they ask you if you are going to Belize. They will ask this if they see Belize stamps in your passport. I tend to stay on the US highway system as much as possible and cross at McAllen. Make sure you have insurance or you may not get out of Mexico or if you do, it will be on foot! Laredo sounds interesting. The hardest part, for me, was getting out of the stupid border town, not that bad though. Mexico is a great country for a road trip. My parents make the trip often as well. My last trip I left downtown L.A. early Sunday morning (after a night on Sunset Strip) and pulled into Corozal on Tuesday evening in time to hit the slots (felt lucky).