Bry,
You really need to think about planning a trip that far into Mexico. 10 years ago I would have probably followed you down there. Today is another story.
You have several things going against a safe trip. The main concern is that you currently have a M/H that is 15 years old and subject to a major breakdown on a trip of that nature. Finding a qualified mechanic, let alone parts, will be difficult.
I've driven all over Mexico and I can tell you that roads are not their priority outside large cities. Your route will take you through some rough travels on the roads.
Today, Mexico's economy is in the tank. People struggle just to eat. If you leave your rig for just a minute you can plan on getting something stolen. You will look like a rich American and a target for a possible robbery or your life will be in danger.
You can't trust the Police either anymore. Corruption runs through the ranks.
Then comes the drug cartel's. They ARE REAL and DANGEROUS. If they want something you have they will just take it right in front of without batting an eye.
Mexico IS NOT SAFE ANYMORE. DON'T DO IT.
It's so bad that I have 2 friends that lived in Mexico for years as American Nationals. They bought homes in communities where other Nationals live. It got so bad where they were that they just packed up and headed back to the states leaving their property behind. From what they have told me others have followed.