Once you have established your latest check-in time and come up with a clearer communication about 'no kitchen use, no restaurants open', the only thing left to address might be what to do about the guests like your last one. They arrived hungry and with no options for a meal. Like you, most of us would find it hard to ignore someone in that situation and yet, it is not fair to have to absorb the cost of feeding them.
A possible solution might be to have a small selection of non-perishable items set aside in the corner of your cupboard to offer in such situations...for a set price.
For instance, option No. 1 is: Two packets of an instant chicken or tomato soup mix (i.e., Cup-a-Soup, or similar), a sleeve of plain crackers, peanut butter and honey for two. It makes for a satisfying late night snack and would quell the hunger pangs.
Snack option No. 2: (come up with something that also doesn't create cooking smells.)
The charge for each late night snack-pack -- double the cost of what you paid! If the guest chooses to purchase, you will make extra money; if not, it is off your conscience that they go to bed hungry.