I can do about 75 slabs without doing any reheating but if you want to sell 200-400 slabs like a lot of rib burners do then it's undercook, reheat and toss on a grill and serve. 2 hours max. Having the equipment to cool is the key.
I don't like vending ribs because once they reach a certain doneness there's no reheating. And I hate selling undercooekd ribs. I'm sure some of the rib burners here will chip in with advice.
Retired competition cook. BBQ mentor.