The days of crappy gas in Mexico are gone. Gas is sold by Chevron, BP, VP Racing Fule and plenty of other. Because of fewer additives my truck gets better mileage than in CA.Just bring a case of Techron, and a spare fuel filter to Mexico, for gas engines.
Likely didn't burn because it was mostly water.
I drive a 2500 long bed 4X4 with lockers, gas powered. It gets me most everywhere I want to go. I am going to drive the Pan American taking 6 or 7 years. The two extra feet of living space out weights all other considerations. it goes to Mexico almost every month. It is currently set up to carry my toys, when I go to a pop top, I’ll be trading off mobility for comfort and softer living. Everything is a trade off.
If you are thinking of living on the road you might look up work campers. There is plenty of temp work and free living out there.