Full-timer taking Airstream into Mexico - Help!

Don't sweat the small stuff. As stated above, very high end coaches enter Mexico all the time with lots of great stuff.
Just review the rules as to what you can re enter the US with, and you are covered. Believe the rules for re entry, just because the meat, booze, whatever was purchased in the US and taken down with you DOESN'T mean you can just re enter with it.
Have a great time, don't worry about the small stuff-it's all small stuff!