gistfile1.txt

1000 sausages = 11 large crates (96 sausages per crate)
1000 bread rolls = 20 large crates (50 rolls per crate)
300 soft drinks = 13 cartons
120 water bottles = 5 cartons
40kg onions = 8 big bags
40kg ice = 8 big bags
6L bbq sauce + 6L tomato sauce + 2L mustard = 2 crates
1500 serviettes = 1 large crate (15 packs)
6 eskies (store cleaning stuff in eskies)

TOTAL = 72 items to carry (one item carriable per person)
Therefore, with 8 people fully available and no car,
that is at least 9 round trips per person.