I am probably not answering your question, but I try to think of things that are neat or neater & easy than if we were eating at home.
For example, at home I might serve a cream cheese on a cracker. If we are at a picnic, sitting on a blanket, with lots of distrations I may instead serve cracker with a slice of cheese on the side (+ other things but my point is the neater the better.)
Maybe I am overboard, but sometimes I consider will the berries I am serving stain my lo clothes, my clothes, those around us, the blanket?! In that case, I may bring grapes or apples instead of raspberries or blackberries.
Sometimes I may choose things that are more of a treat and make sure I get in all the other things she needs at other meals. So, if veggies are the food we are boycotting for the moment, then I may skip those at the picnic and serve at dinner instead.
My friends were teasing me because my lo was on a kick where she loved crackers with a cream cheese or guacamole spread topped with meat. They all said it looked like I was serving her appetizers. She loved it and they were the right size for her to maneuver.
I am sure we have all noticed that lo like what everyone else is eating. Maybe pack a little more to share if there will be other lo around that you know.