Two years ago my wife shipped her house to Mexico, we used a freight service "Transportes Castores" that provided a 53 foot commercial trailer and used the services of a Customs Agent and we had to take some of the stuff with us in the RV and the toad since it did not fit in the huge trailer we had the original copied so that we could use it at the border, they never bothered they were practicing with the X-ray and Gama machine, and that was it we where on our way.
The most important document is the Menaje de Casa inventory with the Consulate Stamps and signature, you will notice that at the bottom of all the pages they will cross out any blank space so that you can not add anything else.
When you get to the border go directly to the area of the Aduana "SAT" and have your Mexican Immigration papers and the Menaje de Casa ready for the agent, chances are that they will look for a few items in the trailer and the back of the truck, make sure that you have your copy not the stamped one but yours so that when the agents asks for an item you have an idea of where it is located, it is a good idea to make a small map of the various items as you pack them, that helps to point the item and the location and speeds the inspection, also have all the cats and K-9 paper work handy.
Since you are transporting your possession you do not need the Customs Agent although check with one just in case that the SAT has changed the rules.
You might spend a few hours or they might see that you have the correct paperwork and let you go on your way.
Bien venidos a Mexico, me voy a tomar un Tequilita en su Honor!
"Welcome to Mexico, I will drink a little Tequila in you honor"
navegator