That is a good idea. Subway does something similar you're just leaving out the bread and putting cold cuts with a salad. Maybe not as fulfilling for some but its something that could be used for quick preparation. Thank you.
Crackers does not fall in the sandwich category . You can layout crackers with cheese and square cuts of ham or anything you like on top. Depending on the size of the cracker you're using 5-10 should be a good enough snack to keep you going til the next big meal.