Air conds are provided by you?
Anyway, you did a very big mistake here.
If I were you, I'll measure each appliance's maximum draw(set to lowest and blower speed at max) for 2 hours and take measurement. Like if 2 hours using 2 units, then 4 air conds will use 8 units for 2 hours. 1 day would be 48 units. 30 days will be 1440 units. The water heater, WM and others. Get the average out and calculate.
Then from there you set a price of a room rental, this can avoid your problem.

Nope, I never think of this. But my friend have this problem from people that rented his properties.
For me, if were to avoid any problems, water and electric meter I won't provide, simple. Only can't ask for high rental.