I work 12-16 hr rotating swing shifts. Should I increase my food intake on longer days? I'm hungrier on night shift and longer shifts

Try finding carb friendly snacks to eat on the long days. Pretty much in a similar situation as you so on my long days, I keep 100 calorie packs of almonds around to snack on and some hard boiled eggs in the fridge. Then just focus my meals on being low carb to keep my daily total under. 

I know it is difficult, but try to carry at least 2 meal boxes and some snacks for munching and Stay hydrated always. Your efforts and hard work will keep you strong, stay blessed.