Depending on how the ceremony space is divided I would either have the cocktail hour in the same space as the ceremony or move the guests into the reception area early. I would of course have to a mariachi band playing during the cocktail hour and continuing into the dinner part of the reception.
This is a picture of the Mariachi Cobre that plays daily at the Mexico Pavilion at Epcot. Do I think I'd actually get them? No, but it would be really cool! I'm sure there are plenty of similar bands that would work for my wedding.