@Melinda396
I would say a bad review just because the Guest is angry sucks, I know I get Them but I look at it as a lesson what do I need to do differently so my rule but no conflict.
The exterior cameras is probably a good idea.
I would make Guests aware in a positive way, House Manager visits the exterior of the property daily in case you need any assistance. That also says to the rule breaker, we will notice.
Also I totally understand the cost issues of even 1 person. I rent private rooms 2 people max. My pricing is set up for 2 people. Majority of my guests are 1 person but longer term because work so a girlfriend or wife might visit for a week, I am covered and they love no extra cost I think only once someone who was 1 person and I gave him a $5 per night discount and he booked immediately. Maybe you should review your average bookings and think maybe pricing for 4 is too low?