Smokinit is right on track. Pulled Pork and Brisket Sammies are a great way to start. We run both sammies, bbq nacho, Hot links and beans. Something else to keep in mind is presentation and price. Give them a large sandwich for the price. We use a 4" bun with 4-5 oz of product. We were running our sammies at $6 with a larger bun and an 6-7oz product. They sold ok. I dropped them to $5 on a smaller bun which made the sammie look bigger and I'm selling 3x as many sammies to the same crowd.
As for ribs, they are a pain to vend IMO. Hard to eat on the go and you will go through alot more of your consumables (Napkins, boats and sauce) in the process. As the others have said, use the ribs and chicken for a Friday or Sat night special. People will plan for it. Hope this helps.
Big Daddy's BBQ
Concessions and Catering
Louisiana Grill - Whole Hog
30x72 Reverse Flow Offset
16ft Wells Cargo Mobile Kitchen
12ft Full service Mobile Kitchen