I have a bit more info this morning. I have actually been in contact with someone who was refused a permit on a 3/4 ton trying to cross over from La Paz to Mazatlan. He eventually convinced them. On Banjercitos online sign up website, the English and Spanish statements on this conflict. Both indicate that they should not be using GVW. On the Spanish version they state trucks with over 3500 kg cargo capacity. Cargo capacity is of course, GVW minus net weight. For most pickups, this will definitely be under 3500 Kg. On the English version, they state the weight of the truck. I also have a pdf of descriptions of vehicle classifications. Now, I am thinking it would be prudent to take your truck, unloaded to a commercial scale like you see along many highways and have them weigh it, give you a slip and even ask them to put the VIN on that slip, as well as your plate. If they won't do it, most garbage transfer stations open to the public have scales. At least then you have an official looking document with your trucks actual weight as argument. Download the 3 documents Ido have at this address and print them out: Notice the 2 are actual screen shots.
http://www.mexicocaravan.com/permits/banjercito1.jpg http://www.mexicocaravan.com/permits/banjercito2.jpg http://www.mexicocaravan.com/banjercito3.pdfNow I have also heard of them examining the actual sticker on the truck door. I have never experienced this at Nogales where your vehicle is a long walk away, so crossing there is probably not a bad idea. My previous truck was missing this sticker, so another piece of advice may be to peel it off and store it elsewhere until you sell the truck. Then go to a commercial scale and get an official looking slip of your trucks unloaded weight to carry with you. See if they will put the VIN number on it besides the plate.
My registration shows both curb (net) weight and GVW, 2740 and 5100 kg respectively. It is very easy to scan the document, use a program like paintshop pro to eliminate the GVW figure, then apply on line. Since you do not have to use the original registration to apply on line, they would take the net weight figure, which looking at their web site is the one they should be using anyway. Of course if your registration only shows GVW then that is not an option.
My partner is still working on this issue. Things move slowly in Mexico but hopefully he will have some sort of resolution before next season.