You need to go look at the traveling in Mexico/SA forum here. We have been going down for the past 15 years, always with a TC. Diesel is supposedly converting to ULSD, but I'm not prepared to believe it yet. We keep our 2006 GMC as it loves the older diesel fuel. The 2008-2010 trucks seemed to be ok back then, just faster regens. I don't have any direct knowledge about any DEF models. As far as maintenance there, I know of almost no capability for anything more sophisticated than the old 7.3 Ford, as none of our current trucks seem to be sold down there and the semi's are different animals.
The biggest problem these days is getting a the truck in the country as due to some poorly worded rules and atruck over 3500kg is deemed a cargo ie commercial truck. They didn't say cargo capacity, just the weight. Many have been turned away at the border. Discussion of this topic could go on forever. Read the Mexico travel forum. Some how the 5'ers get in, I haven't figured that out.
We will be crossing in Texas next week, but we got all our permits on line which will reduce the chances of getting turned away.
Bottom Line. If you really want to travel down there and don't have a rig I would go find a small 23-25' class B or C that runs on gas(no Sprinter's). Every road we have found is a 2wd including the back roads of Copper Canyon. We have used 4wd one time getting off a beach.