Belize is all the way on the other side of Mexico. That's a Country that has a huge corruption issue in their government and law enforcement, not to mention the drug cartels killing people all over the place. I'd much rather take my chances with the criminals in the US versus going through the criminals in Mexico.
I can say if I ever did get brave enough to make a trip like that, I wouldn't do it unless I was with a trusted guide that was very familiar with Mexico and spoke the language. No way would I just head out on my own.