Unless you're running a trunk full of drugs up the coast for the local narco-gang you should be fine. I've had conversations here with septuagenarian Americans who drive RVs all over Mexico without any problems. It's best to avoid driving at night, mostly for the livestock that wanders on the roads, and because the road conditions are hard to judge, but also because most of the nefarious activity occurs at night.
Of the 47,500 people killed in the 5 years of the narco wars, none of them were tourists deliberately targeted by the gangs. A handful have been killed or injured in crossfire, but the chances of that happening are very, very slim.
As for road conditions, I can't say.... hopefully others here will be able to help you.
Phil from the safety hub. over 7 years ago