Having led several RV caravans into Mexico with all types of rigs, I can tell you smaller is better. Truck Campers are not necessarily best due to height issues, a lower shorter travel trailer, class C or class B are the easiest. Large rigs like 5th wheels & Class A's are pretty much restricted to toll highways or highways that the dirver already knows are OK. 13.5 & up BTU A/C's are not practical as most RV parks are 15 amp only. I would not personally boondock in Mexico unless in a group. If you are looking at diesel you alos need something pre-mid 2007 as thr eis no ULSD. Not a big issue for one trip, but if you plan on continuous ones you will evntually have issues. You might want to look at Amigos Rodantes caravans one way, which run into the Yucatan for a first trip to learn the route & ropes if you have a larger RV.