Honestly, that sounds like some refreshing fun. Have the cook with a big grill out front, and putting in the order is just chatting with them.

"Hey, bud, you want a burger, hot dog, steak, or some of this brisket I been smoking since this morning? Want something to drink? There's beer and soda in the cooler, or we got tap water. The little cooler has juice for the little'uns."

And then have a cashier keep track of what they had, conveyor-belt sushi style. The cook chats with whoever is standing around drinking a beer with them (and is drinking beers or soda or whatever all shift), and everything gets served on paper plates. And the tables are all those wooden picnic tables with cheap plastic tablecloths.

And those who are eating there are encouraged to stand around and chat with other people as well (if they want). Just make the whole thing like a backyard barbecue with your neighbor Hank.

And hire nothing but retired men and women working part time as the cooks. Nothing but grill daddies and mommies, working just for some extra cash and the fun of barbecuing. I would take that job when I retired in an instant.

Edit: better yet, make it habachi-style, where there's a grill daddy/mommy for every group or two, set up like a park barbecue. I love this and want to go to one or work at one now.