Why are you bringing the oil? Is it to add flavour or is it just to add calories. If it is just to add calories I would leave it behind because on a 1 night trip if you end up in a negative calorie balance it doesn't really matter.
If you wanted to replace the calories I would add some whole nuts. Peanuts, almonds, cashews are all over 6 calories per gram and usually can be found unsalted. Although if it his hot out salted nuts might be better.
Also for the tuna if you get it packed in oil its calories per ounce go way up.