Maybe I was confused by the wording of the question - they asked about companions for "safety/security" but also mentioned Pan American Highway which to me sounds like they will continue on beyond Mexico. My reply meant to address the "safety/security" subject - we do not feel we need that in Mexico anymore than we might in the US. But to me traveling further south than Mexico would be a most definite "safety/security" concern - in fact at this point in time I would not go to most of the Central America countries though we have been in the past. The vast majority of the violence we hear about in Mexico has to do with drug gangs killing other drug gangs. There may be other crime but it is no more of a concern to us than what happens in the US.
The original poster has not responded to any of the responses so we don't really know what they want or if maybe they changed their minds or are not that serious about it. I think they need to tell us more about their plans/hopes/dreams to get better answers to their questions.