Girlfriend wants to take a trip to Mazatlan, MX and take a side trip to Tequila, MX. Looking at the area it seems rather touristy (which is good in this instance) but I'm more concerned with the Tequila side trip. We'd be taking 15D the entire way during the day both ways and spending one night in Tequila, MX before he head back the next day. Basically what I'm getting at is... How safe is this trip overall? I've looked at the State Dept site and I'm not seeing too much with these places in particular.

You might need an international driving permit as well. I'm not really sure how they count the 300 mile rule. Why not just see if you can pay a tour company and worry a bit less about everything involved?