If your target market is largely Central American, empenadas may be your answer. These are square pouches filled with various ingredients, then deep fried...similar to a hot pocket. When I lived in Washington, D.C. some 15 years ago, there was an empenada restaurant near Adams Morgan (on Columbia?). Fast food, easy to take and go sounds good for your immigrant worker target pop.

As somewhat of an aside, I've always thought that in a college town, a simple stand selling tamales and soppapillas from about 5pm to bar closing + :30 would be a big hit.