The minimum equipment is going to vary a lot based upon what you intend to cook, how much you are inclined to rent as needed, how much you can charge and what venue you intend to sell. If I was going to do it...
1 large smoker, capable of at least 250 pounds of meat at one time.
2 electric cambros, with enough service pans to fill them.
4 tables, with extensions
2 canopies with one complete set of sidewalls
4 large ice chests
chafing pans, service bins, lots of cooking utensils
portable triple sink
Those items will makes life a lot easier. Get a trailer unit with a large gas burner for frying, boiling or beans. Makes life easier. Gas assist in fire box is real nice too.
me: I don't drink anymore
Yelonutz: me either, but, then again, I don't drink any less