That is a tough one big. Can you get any feedback from the folks that did it last year? Was there a last year? Pulled pork is pretty easy in that you can always freeze what doesn't get pulled but those ribs are a bear to figure. I did an event last month, and did ribs. I ran out too soon and was just glad to be done. They had two other vendors there and I am pretty sure I was the busiest of the three of us. The others were burgers and fish.
Hope you got a couple cambros. They make the job easier.
I guess the big question is how many folks are you figuring on feeding I am thinking 10% may be sort of high because I am thinking that you are not going to have enough time to attend to 800 folks? I agree with Bubba, sell out and you will be doing just fine.
I guess I would figure on the hours of the event and figure you will be very busy from noon to six. Even at 600 folks that is more than one per minute and that seems a little high too. I am curious to know how that works out. Unless you have a lot of help, you have your hands full. So I didn't put that into the consideration.
Some of the things I am learning is that there are easy foods and hard foods to serve. Easy means that you don't have to attend to them, such as dogs sausage and meat that is presliced or pulled. Ribs are high maintenance as is tri-tip when cooked to perfection. And of course chicken dries out regardless due to sitting.
Concentrate on the pulled pork and links. yeah baby! The links can be frozen to cooked in a few minutes.... well if the heat is high enough that is.