When we do catering events we have to move a lot of food and equipment. When we do new menus and locations we will actually do a dry run and set everything up and run through how the service will flow. At the end we will pack up the equipment we used and then some other back up equipment. This usually has us in a very good place for what we will need.
So with that process in mind. Do a set up in your back yard or driveway and run through what is needed and see what you have to go inside for. Then add that to your list of to pack for an event. You can even do test runs with your food and do the same process for ingredients.
Truer words...........
I have never done BBQ, but I did for a few years do Chili. There is nothing more important that you go thru a complete cooking before you hit the trail. I would pack up, drive to the shopping center's parking lot, and cook just like I was in a contest. Equipment run, usually donated the chili to the Mission. No going home for items that way. I would also recommend that you do it in the rain. Make your lists, label all your equip containers both taped to the outside and a sheet on the inside. Set up and tear down in order so you know the tarp lines weren't at the bottom of a box put up some where, you know what to look for. Throw a composition book in one of the boxes, list what you see the others doing that intrigues you. ideas, complains, notes.
Remember you are not cooking for you or your normal customers, if its close to where you live drive over one Sunday and try that towns best. Usually at least 1/2 the judges are home town personalities. Each town is proud of their best and will always tell you were to find it. I was beat in contests by chili I wouldn't have feed to my neighbors dog it was so bad, seriously who puts bell peppers and mushrooms in chili, let alone BEANS?. So don't take it personal. Its about consistency, and it being right that day that its your turn.
Its nice if you can enjoy it too, I didn't see many who did. Too stressful, too secretive, too nervous, too drunk, too familiar..... Just do your thing because you want to get out on the road, have faith, and keep lighting those pits. Course BBQ might be all different, but then again it might not.
Good luck.