I made this trip in a pickup truck and I have a ton of advice built from my own experience.
First, do not drive at night.
Do not camp out.
Find hotels with a parking lot close to your room.
Figure out a way to securely, and seriously, lock your motorcycle to its trailer or whatever.
Take two spare tires.
Take at least one 5 gal jerry can, keep it filled.
DO NOT try the drive with a vehicle that is financed, i.e. has the banks name on the pink slip, you will not get across ANY border.
Go to AAA and find a way to get multiple "originals" of your pink slip and registration. Most border crossings will NOT accept foto copies. Do the same for your motorcycle. If you cannot get these multiple originals, you will need to go to a foto copy place near each crossing and have the copies notarized before the customs people will accept them
Do NOT drive thru Mexico City. Stay on the Pacific coast.
Have everything organized so the customs people can see it easily without emptying out your truck.
At every border, you will see a line of 18 wheelers waiting for hours or days to cross the border. You do not need to do this. Drive past them to the immigration/customs location.
Be prepared for each border crossing to take ours. What I did was stay in the town at the border the night before, be first to the crossing in the morning. Then you will have to go to the next countries process. By the end of it, you will want to stay in a hotel on the other side, so plan on each border taking a day. when you get to the borders, people (sometimes young men) will try to get you to hire them to help process you thru the station. Use them. They know everyone inside the office. (and they know where the Notary publics are if you need copies.) This is how they make their living. The customs people appreciate you using them, they are all probably related. BUT SET YOUR PRICE BEFORE YOU HIRE THEM.
Have PLENTY of blank pages in your passport. You will get one full page "visa" for your pickup, and another for your motorcycle. That is TWO pages PER country. You can get extra pages in your passport before you leave. And remember, your passport must be valid for at least 6 months from the time of entry.
You may well be stopped (especially southern Mexico) by military people. Be very nice, seek out and speak to the officer in charge, compliment him on the beauty of his country and how nice all the people have been to you, and offer before he even asks to show him all your goods in the truck. It goes without saying that you should not have any arms or as much as a rolling paper in your vehicle.
Take your time, do not set a schedule. Stop and stay places where you are comfortable.
Write me back with questions or comments, and have a great trip! :sombrero: