Personally - I use a 1 qt day bottle in my flight box.

The idea is that;
1- you are not going to use a gallon, so why carry it?
2- the gallon jug is heavy, why carry it?
3- If you are not careful you will 'COOK Off' all of your nitro before you finish the jug.

So - I got a 1 qt Orange Juice plastic bottle (Square) and I fill it up as required. I keep the "main jug' at home nice and safe.

Works great, costs nothing I'm happy!