It is not a problem to travel here with your tear.
You must have the registration for you tow vehicle and the trailer.
As you cross the border you must get a visa(after the first of the year, you will need a passport) and then just go the bank (right near usually) and get your "permiso" permit for the car and trailer. There you will need copies (there are people around to make them) of your registration, visa and drivers license. when you get to the window give them the originals, copies and your credit card. They mess around a while and then hand you a permit you peal off and stick in your window. That is all there is to it. As you leave Mexico, you must turn in you permit. If not it will be very difficult to get another later on.
Some times the "Transito" police give you a little hastle. Usually 50 Pesos (about $5) takes care of it. Normally not, but you never know. Remember, only the customs agents and the federal police have any power over your vehicle. The transito can only give you a ticket, but normally the 50 pesos takes care of that.
Basically, do not be afraid to drive down here. Just before crossing make sure you get insurance for your length of stay and then you have no problems if you have an accident.
Write me a PM if you need more info or ideas where to go. By the way, I live in a Mexican tourist town. We have friends that can take care of you while you are here. Oh yes, I will also offer all the help I can.
Get the book by Churches:
CAMPING IN MEXICO.
It is a great book.
We are day trip away from the most restored pyramids in Mexico (Tajin)
"Essie" and the Mexican Tear