How can I have great sales at this event?

I work next to an independent bookstore that’s having a reading with a popular children’s author tomorrow. They’re expecting a big crowd (maybe 2000 people) so they will block off our shared parking lot for this event. Restaurants in the neighborhood are invited to set up a table and sell whatever we want. Other than my place (our most popular items are sandwiches, salads, and coffee), there will be the bookstore’s cafe, a pizza restaurant, and a Mexican restaurant.

Today I asked my manager if he has a plan. He says he forgot about it and will be off tomorrow, so I can put together whatever I want. He said that sales were disappointing last year, but we only offered cookies and brownies. I’m the assistant manager. I’m opening the store tomorrow, and the event starts right after my shift ends and goes til about 6pm. So I’m looking at a 12 hour day.

The bookstore cafe will be selling sweets, and then we have tacos and pizza from the other two restaurants. I’m trying to put together a concise, healthy menu of food that can be eaten standing up. I’m also including things that are impulse buys or are very popular sellers. It will be mostly kids and parents, and it will be super hot outside.

Here’s the menu I have so far:
Ham and brie sandwich with dijon mustard 6.75
Caprese sandwich (tomato, basil, mozzarella, and vinaigrette) 6.75
Pita chips 1.49
Kettle chips 1.49
Giant chocolate chip cookie, oatmeal cookie, or white chocolate raspberry cookie 1.99
Apple or banana .98
Iced coffee 2.39
Naked juice berry blast or naked juice orange mango 3.79
Orangina 1.89
Perrier 1.69
Fiji water 1.59
Vitamin water 1.89
Fresh orange juice 2.99
12 oz. tropicana cranberry, grape, or lemonade 1.89

We pre-make the sandwiches in the morning, so that will be easy. I think I have too many different kinds of drinks, but I don’t know what to get rid of. I’m not sure whether I want to include yogurt or ice cream bars- it might be too hot, even with a cooler.

My resources are a table, a chalkboard sandwich sign, an umbrella, and a cooler. One employee will be able to help me if things are slow in the store. This is kind of my project, so I want to do things well and make a ton of money. Any input? Thanks!