Plan tailgate food and supplies.
Tailgating has one constraint a backyard cookout does not: everything has to arrive cold and stay cold in a car park, often for hours in the sun. That makes ice the item to plan properly at around two pounds per guest, which is double a normal party allowance because coolers are opened constantly and sit in ambient heat. Meat at seven ounces a head is a shade under a backyard barbecue, since tailgates usually run to snacks alongside. Drinks at 1.25 per guest per hour reflects a longer, slower event. Fuel plus about fifty cents a head for plates, cups and foil covers the disposables that never make the shopping list.
Tailgate Planner
Meat lb = guests x oz per guest / 16; drinks = guests x hours x drinks per hour; ice lb = guests x ice per guest; supplies = fuel + guests x 0.50
Food safety matters at outdoor events: keep cold food below 40 F, cook meat to safe internal temperatures and discard perishable food left out beyond two hours, or one hour in hot weather. Check venue rules on grilling and alcohol before you go.
Two pounds per guest, and more in hot weather. Pre-chill drinks before packing so the ice is keeping them cold rather than cooling them down from room temperature.
Keep raw meat in a separate cooler below 40 F, use a thermometer, and do not let cooked food sit out more than two hours — one hour above 90 F.