I tried to send this privately but it was returned .. so I'll post it here.
While I'm not so fastidious about refrigeration for myself and have never
gotten sick from such things, I personally wouldn't be willing to take any
chances with the health of other people. I don't know if you have to carry
this far by hand, etc. .. and, if so, this may be impractical, but I'd be
inclined to freeze water in milk cartons or something like that and invest
in even an inexpensive ($1-2) foam ice chest or two. The risk of food
poisoning is just too high after 8 hours, for my conscience. Whatever beverages
you may be serving could be frozen, too, like how I used to send a frozen
juice carton in my son's lunch pail for safety. Some variation on that
(bottles of juice, for example) could work.
Spicy bean spreads are delicious as sandwiches, I think .. inexpensive
and easy to make in bulk in a food processor. If it's on flavorful bread
(mm .. onion or rosemary, etc. .. easy to make, if you're into that),
imagine what a treat that would be. If you baked focaccia 1-2 days before
(or earlier and froze), then sliced it in half (like cake layers) and
spread the bean spread, it would be less work than making individual
sandwiches, I'd think. Ooo, I like that idea, myself. Come to think of
it, you could make the sandwiches ahead, freeze them and not have to worry
about refrigeration much at all (I'd still freeze a few quart bottles of
juice to be on the safe side, though).
How many in your cast/crew to feed that night? I have recipes for
large groups that may help you to judge amounts. Hmmm, wonder if there's a
website for picnic recipes, which is essentially what you're talking about.
All the picnic things I've ever looked at before warn strongly about
Another idea is making burritos (labor-intensive .. but not much more
than making individual sandwiches). Those can be made ahead and frozen,
for sure. I do that fairly often.